I wanted to make a big long post about it, but I can't seem to get in the mindset, so here's the short-short verison:
I loved BioShock2. I don't know if it's as good as the first (there can only be one first time to Rapture) but I think it is. If that makes any sense.
I'm playing Assassin's Creed II now. I really dig it. It's extremely well done, a HUGE improvement over the original and a very good game all around. If you looking into AC1 and gave up on it, it's probably worth checking in again with AC2. It's also on a pretty decent deal on gamefly currently.