1)An odd little episode, most of which is concerned with what it would be like to have the Doctor as a roommate. As such, it's got a number of amusing moments, with the Doctor making awkward attemots to be "normal". I gather James Corden is pals with Matt Smith in real life - they certainly play well together, making a good comedy team. We also get to see the Doctor as matchmaker, which is also kind of funny.
2)Amy's largely absent from this episode, although she does get a moment at the end, where she finds her engagement ring in the Doctor's pocket.
3)Some fun quotes:
An OK episode - Craig's a fun character, and the baddy was cryptic but sufficiently attention-grabbing.
[Part of list of Doctor Who episodes here.]