The episode got off to a good start, and I liked seeing the Doctor climb out of the TARDIS (lying on its side) via a rope. It makes sense, given the concept that it's bigger on the inside, but it didn't immediately occur to me. I'm a bit dubious about the new theme tune, but maybe it will grow on me.
When the little girl was introduced, I recognised her name (from advance publicity), so unfortunately that gave the game away, i.e. I realised that the Doctor would be gone for significantly longer than 5 minutes. Similarly, when I saw the adult Amy wearing a police uniform, I knew it wasn't real because one of the tabloids revealed that a while back. ("It’s going to be a bit of a shock for the fans." Well, it would have been if you hadn't just told everyone!) Ah well, no matter. Admittedly, I did choose to watch the trailer bit at the end of the episode (which I normally skip), but hopefully that doesn't give too much away, and it all looks good.
When I first heard about Matt Smith becoming the new Doctor, I had two reactions.
a) That's a stupid hairstyle.
b) He's too young!
I didn't really mind the fact that he was the youngest Doctor so far, it was just that he was the first Doctor who was younger than me at the time I first saw him. Still, he did a good job, and I agree that he's portraying the Doctor as a bit bonkers. I'm happy with Karen Gillan as the new companion too; she reminds me a bit of Felicia Day.
There were lots of bits in the episode that made me laugh. The only bit that didn't quite work was Prisoner Zero, since we never actually saw this deadly snake hurt anyone. Why didn't it munch the three of them in the hospital ward?
As for the new-look TARDIS, the main thing that got my attention was the St John Ambulance logo on the door. Doing some digging online, this was apparently there in the very early episodes (with William Hartnell). The real police boxes had this logo, because they kept a first aid kit inside. Anyway, this seems like good publicity to me, and I'm happy to combine two of my interests. I'm not sure how obvious the logo was to non-Johnnies, but I'm sure that some of my colleagues will have spotted it.