You're right about Adam and Hiro but I really think that the finale sucked! I'm aware that they had to wrap it up quickly because of the strike (damn you corporate America) but it still feels like they didn't make much of an effort.
Anyway I found most of season 2 pretty dull except for certain episodes. I'm really disappointed because season one was really good. Claire is boring and annoying, the mexicans are annoying too, the way Peter is so stubborn doesn't feel real and I dunno, the story is just not as interesting. Thank god there's Elle, Sylar and Adam :)