I played AC2 and Brotherhood virtually back-to-back and it was a great experience.
Probably the only criticism I could hold against Brotherhood is that even its blatantly cliffhanger-y ending didn't manage to make me care about subsequent games in the franchise - which, given the response to Revelations and AC3, probably wasn't even a bad thing
I'm very much looking forward to playing Black Flag, however (which I'm content to wait for until I'm getting a NextGen console).
Probably the only criticism I could hold against Brotherhood is that even its blatantly cliffhanger-y ending didn't manage to make me care about subsequent games in the franchise - which, given the response to Revelations and AC3, probably wasn't even a bad thing

I'm very much looking forward to playing Black Flag, however (which I'm content to wait for until I'm getting a NextGen console).