Well, I really only have this to say: holy fuck.
It started off with a bang, Clara trying to communicate with all those Doctors. Thanks to the lower picture quality of the older material it even looked like one of the crappier colour separation overlay scenes from the old show. An unintended additional homage.
And then it ended with an even bigger bang. I thought the episode would end with Clara being trapped in the timestream and the Doctor jumping in after her. Then the anniversary special could have been the two Doctors teaming up to save her. But instead we got something much more intriguing, a non-Doctor Doctor.
It has the added benefit of making sense out of the Doctor's name mystique. I quite like that.
There were some minor weaknesses towards the end with the pacing. It was all a bit too much exposition for my taste but otherwise it was fantastic. I did love the scene where we see the first consequences of the Doctor's timestream being poisoned when Strax tries to kill Vastra. That actually felt more terrible to me than the stars disappearing.
I must say that the whispering men were terrifying villains. That scene where they were about to kill the Doctor's friends and were unstoppable was great.
I'm sooo looking forward to the anniversary special.
I've only watched it once so far. Is it just me or does Tennant seem a bit out of place in the Doctor's costume? It's funny because he's still my favourite Doctor and Matt Smith is actually my least favourite one but somehow seeing Tennant back in the costume looked odd to me.
The anniversary special will be awesome.