It's fair to say that this week's episode of Doctor Who has had a lot to deliver. Showrunner Steven Moffat has been slowly teasing answers over the last two seasons, so it's natural that fans have been hoping for this season finale to tie up many of the loose ends generated by both this season's events and the last. And it is only fans that are waiting for it, because as a casual viewer you just cannot come in at this late stage, as you won't have a clue what's going on.
Most of them are fortunately tied up (with the exception of the question as to why the TARDIS was blown up back in Series Fnarg, or Five to you non-Moffat fans), so it's nice that the episode wasn't disappointing in that respect. Of course, I don't think anybody believed that the Doctor was actually going to die permanently at Lake Silencio (especially considering that Matt Smith is staying on for at least another year), but now we have an incredibly obvious explanation for how he escaped it.
That explanation comes in the form of the Teselecta, the shape-changing robot controlled by miniaturised people introduced in "Let's Kill Hitler". At some point before the lakeside, the Doctor stumbled back upon them and asked them to take his form and pretend to die in his place while he was safe inside it. Unfortunately, this explanation doesn't really hold up when you think about it. My main problem with this (leaving aside the fact that the Teselecta can apparently replicate a Time Lord's regeneration ability as well as appearance) is the fact that unlike the Teselecta introduced in "Let's Kill Hitler" (which had clearly robotic mannerisms and made whirring noises), this one actually moves like a person. I can understand why it had the Doctor's voice but not why it had his movements.
One of the central ideas behind the episode is that because of River Song choosing not to shoot the Doctor at Lake Silencio (her love is so strong she can change a fixed point in time, isn't she special?), a fixed point in time was changed and an alternate timeline where time froze at the point of the Doctor's death and all of history happened at once, so London was filled with Mini Cooper hot air balloons and Pterodactyls attacking children in a park. This led to a world filled with wonder, whimsy and Winston Churchill, and as such it was a shame to see it go to be replaced by the normal timeline. I for one would've been interested in seeing adventures in this altered universe, although time travel would've been rendered both impossible and unnecessary.