Well crikey.

Perhaps we’d all better start by sitting down. For if you were awaiting a simple, easy-to-explain blockbuster of a Doctor Who series finale, you simply didn’t get it here. Instead, if you were looking for something really very ambitious, often quite confusing, yet ultimately far more satisfying, then The Big Bang absolutely hit the mark. Warts and all.

For the avoidance of doubt, let's make this clear: we loved it. Even if our head hurts too.

After all, just look at what it managed to put together even before the credits rolled, as for the second week running, the kicking in of the theme tune provided just enough time to scrape our chin off the floor.

We had the understandably lengthy recap of The Pandorica Opens, and then we moved on 1894 years to where this series all began in The Eleventh Hour, with young Amelia Pond saying her prayers. That alone was goosebump good, confirming – as if there had ever been any doubt – that this was the most intricately plotted series of Doctor Who quite probably of all time (sorry to anyone out there who holds much of a torch for The Key To Time or Trial Of A Time Lord). It seemed that pretty much every episode fed into the bigger story, and it certainly paid off big time with The Big Bang.

The opening, once it had got a Richard Dawkins gag in, soon went about the business of getting young Amelia to the point where she discovers the Pandorica in the British museum. But what’s this? Only she can open it, seemingly just by touching it? How does that work?

And there’s an even bigger conundrum: for when it opens, an older Amy Pond is inside, alive and sort-of-well. How’s that for an awesome opening right there, and one that had you wishing you could fast forward through the credits sequence straight away? We're amazed our neighbours didn't knock the walls as we screamed at the telly. Our ASBO is no doubt in the post.

Puzzles

Fortunately, the puzzle of what Amy was doing there, and how she’d survived 2000 years in a box without dying was one of the easier to explain moments of what was a complex episode (courtesy, in this case, of the Doctor’s explanation of the fact that the Pandorica holds its prisoner in stasis). But it still left one or two questions tickling around the back of our head.

And the puzzles in the episode kept on coming. We soon learned how the Doctor escaped, and how Amy came to be in the Pandorica in the first place. Thus, we zipped back 1894 years to Rory, to whom the Doctor appears wearing a Fez (the Fez being a useful device to help us keep track of which Doctor we were seeing, as well as fuel for a couple of neat comedy lines). These appearances by the Doctor, we later learn, are the result of some time vortex travel, where he’s travelling directly from the British Museum nearly 2000 years later (for a crude form of time travel, incidentally, it seems to work a treat here).

Thus, Rory is told the Amy Pond he holds in his arms isn’t dead, that the universe is ending, and that he needs to help the Doctor get out of the Pandorica. Oh, and to put the sonic screwdriver in Amy’s pocket.

As a result, the non-Fez-wearing Doctor is unlocked from the Pandorica all those 1894 years previously by Rory with the sonic screwdriver. We’re told it’s future Doctor who appeared to Rory, although that doesn’t really answer the question of how the Doctor could get the message to Rory in the first place. After all, for a future Doctor to appear, surely he had to get out of the Pandorica himself at some other point, else how could he relay the message to Rory in the first place?

Several theories there. The most potent, though, is that time, after all, is collapsing here, and as the Doctor has suggested, time isn’t a straight line, time is a curve. Plus, we’ve seen the Doctor crossing his own timeline quite a lot – and we’ll be back on this point shortly – and that also could have presented an opportunity.

Support

Whatever, the Doctor is released, Amy gets put in the Pandorica, and the drive to save the universe continues. Not before, however, we get a lovely moment for Rory. And it seems right to just have a quick word about him here.

We’ve warmed to differing degrees to the supporting characters that came along with assistants in the Russell T Davies era of Doctor Who, yet you have to say that none – with the exception of Wilf – has enjoyed a story arc and moments anywhere near as compelling as Rory’s. The moment when he decided to wait 2000 years and guard Amy in the Pandorica was nicely done, and in this case was just one of many terrific, quiet moments in a season finale that mainly left all the big blockbuster tactics on the shelf.

Instead, we were getting dense storytelling, and there was more to come. Much more.

Because then we got to the small matter of how to stop reality and the universe falling apart (the stars has disappeared by the time we got to this episode). The answer? A second Big Bang, involved the Tardis, and the light from the Pandorica. That way, using the atoms that had been trapped in the Pandorica with Amy, the universe could be put right.

Clearly there was a strong element of the dreaded reset switch here. But Steven Moffat managed to utilise the device properly, with logic, and with unexpected extra consequences. This isn’t Superman winding the Earth back, or some The Last Of The Time Lords-esque ploy. This actually made sense, whether you like the device or not.

And it’s also used to explain why Amy Pond has never had a family we’ve seen. Because, as it turns out, the crack in time in her bedroom wall has affected her life from day one. That’s why her house is empty, and that’s why she can’t remember that her father appears to be Danny De Vito. And when they all come back, as a consequence of the Doctor’s seeming sacrifice that’s put him on the wrong side of the crack in the universe, it was genuinely terrifically done.

We were expecting to be enraged at any hint that the reset device would be used. As it stood, we found ourselves really quite warming to it.

We liked the stone Daleks too, which proved to be brutal beasts, and left the Power Rangers colour scheme of Victory Of The Daleks out of sight. Instead, we got a Dalek – just as with the Cyberman head last week – who looked as if it would shoot and hit you without a second thought. And as it proved, it did, as it shot the Doctor right out of the blue (although for a series finale, as with most of the series before it, this was very monster-light).

Which seems a good place to stop and ask another question or two. Accepting the shot from the Dalek didn’t kill the Doctor, and that he was ultimately using it as a distraction, it did beg the question why didn’t it end his life? Last time the Doctor was shot by a Dalek, in The Stolen Earth, he started to regenerate. Why didn’t that happen here?

And more to the point, if it was going to kill the Doctor outright rather than cause a regeneration, why didn’t it? This wasn’t radiation poisoning: this was a straight shot that would presumably kill anyone else stone dead. Just saying.

Rewind

Elsewhere, moments of genius kept coming. And none more so than the part where the Doctor’s actions across the last series were rewound (allowing the Doctor a lovely “I hate repeats” line).

If you hadn’t signed up before, this is surely the part where you had to at least appreciate that Steven Moffat is something of a genius. Because the Internet speculation was right: there have been two versions of the Doctor doing the rounds this series. That jacket in Flesh And Stone wasn’t a continuity error, it was – as we and many others suspected – a deliberate inclusion in a delicately structured 13-episode overall story arc. It was brilliant, made sense, and enriched further a series that we’re already keen to watch again from episode one.

Even amidst all of this seriousness, Steven Moffat peppered his script with quotable quips and lines, and ended his maiden run in the showrunner chair with some marvellous work with Amy Pond. The inclusion of the young Amelia was an outstanding decision, and the moment where he declared that inviting Amy along – “the girl who didn’t make sense. How could I resist?” – was just wonderful.

What’s more, ultimately, the girl who waited all that time for the Doctor ended up marrying the man who had waited 2000 years for her, and for once, we were rooting for that to happen.

There was still room to weave River Song still further into the Doctor’s life, although hers are mysteries still yet to come (she’s the woman to call if there’s a Dalek to kill, mind). And there was room too for one last moment of brilliance, with the old, blue book as a wedding present. Something old, something new, something borrowed, something blue? The drinks are on us, Mr Moffat.

And while we’re at the bar, one for Matt Smith. He seems, on reflection, to have had less dialogue than most of his predecessors, and he’s had to – in his maiden run – effectively portray two slightly different characters, and take the Doctor to some very dark places. His portrayal has arguably been as big a triumphant as Steven Moffat’s storytelling, and the Tardis keys are very, very safe in his hands.

Christopher Eccleston is the better dancer, though.

Triumph

The Big Bang was, ultimately, lots of things. It was puzzling, bold, triumphant and brilliant. And a more complex series finale for Doctor Who you may never see again (for a supposed children's programme too, remember).

There are still answers that are set to be puzzled over for some time to come, and there are still questions that remain unanswered.

The riddle of River Song, for instance, looks like it might have been resolved by this time next year, and it may or may not involve a wedding somewhere along the line ("spoilers!"). Furthermore, Steven Moffat chose not to tie everything up with a nice ribbon, by teasing us that the reason why the Tardis was set to explode is yet to come. Plus, who was the voice in the Tardis? What was the silence all about? There are still big adventures and answers to come, and we love that threads have been left untied for the next series.

And heck, off the back of the series we’ve just sat through, and how confidently and intricately it was all knitted together, we can’t wait to find out more. As it stands, we now have the agonising wait for Christmas, which may or may not involve the Orient Express, outer space, and an Egyptian Goddess. Right now, we wouldn’t care if it involved paint drying on the wall.

Because The Big Bang, appreciating that some of its puzzles remain unsolved (and perhaps in spite of it), is the best series finale since Doctor Who returned. Perfect? No. Genius? Oh yes.

Roll on December 25th, and series six next year, then. Because this one is going to take some topping…

Read our series 5 reviews here.