I love this episode, but I think I was kinda let down by it
in 2010. I thought it would explain who blew up the TARDIS but
instead it's about reacting to the TARDIS blowing up. In a way
the lack of an explanation is exciting because it started the
Moffat era's run of big complex multi-series arcs, and I love
that stuff. It's a wonderful bit of misdirection when it looks
like Amy and Rory are leaving at the end but they're actually
sticking around, and the mysteries of the Silence are
continuing. Considering that this episode gives an explanation
to the Doctor's missing jacket from Flesh and Stone (which I
totally called by the way), I trusted that the show would
eventually explain who blew up the TARDIS. Didn't expect it
would take until Eleven's final episode though.
The solution to the cliffhanger - the Doctor appearing with a fez and a mop to open the Pandorica - is just wonderful, both as a bit of fairytale weirdness and as part of an amazingly sophisticated time travel adventure. This episode twists and turns and loops back in on itself but it's never too complicated to follow. Despite not telling us who blew up the TARDIS, everything that needs to be explained for the immediate plot of this episode to make sense gets at least a line. The ending is basically a 'power of love' ending, with Amy wishing the Doctor back into existence, but even that is properly set up. This is just a really well-thought-out script, with plenty of complications but never enough to alienate.
It's an effective finale to Series 5, ending one phase of Amy's journey and starting another. She finally attends her wedding, her missing memories are explained, and her imaginary friend returns when she needs him most. The final set-up for more Pond adventures works so well because Series 5 is a complete journey by itself. Every episode in the series is doing something, whether it's giving more clues about the cracks in time or showing how Amy copes in the absence of Rory. All 13 of these episodes contribute to the overall arc, and they all have that distinct warm fairytale aesthetic. Overall, Series 5 is one of my favourite series, and an incredible start to both the Moffat era and the Eleventh Doctor era.
So The Big Bang is a brilliant finale. It's slightly less focused than The Pandorica Opens, which completely revolves around the moment the Pandorica opens, but it's still a great adventure that takes the highest stakes possible and shrinks them down to four people running around a museum.