The first game is one of if not the single best games I've played this entire generation, and I go back to it at least once every few months. Never had the time for the second game, plus I wasn't really digging what I heard from other gamers about it. Picked it up for four bucks on amazon the other day, and I'm a good 6 hours in.
A lot of the complaints I remember reading about are valid I suppose. It's scenario is no where near as compelling as the first game's. The level design is so-so, and I kinda wish I could go through some of the same levels to see what has changed/if any of what I did in the first game affected the levels at all. However, I dig the gunplay a bit more in this game, and I like that both hands can be used at the same time for plasmids and guns. Makes the game quicker.
I REALLY like being a Big Daddy and hanging out with the Little Sister's, particularly when she's harvesting. It introduces a planning and strategy I haven't encountered in a FPS for a while. When I let her off to harvest, I like to get out my trap rivets, create a perimeter defense, then switch over to anti-personel rounds on the machine gun to take out the splicers. And when they get close? Muthafuggin DRILL. Shit gets intense but with good planning, you make it through pretty well.
I also think the battles are much tougher, thanks to the Big Sisters and Brutes. Reminds me of, like, Left 4 Dead with Tanks and Witches. The Big Sisters are awesome fights, especially if you counter her plasmids with your own. Trying to light you on fire? Freeze her. She throwing shit at you? Telekinesis that shit right back at her.
Haven't touched MP, probably won't ever.
The game is really enjoyable and I've had a good time with it. Lamb seems like a stupid enemy, but eh, so was Fontaine. So far I'd say it's not as good as the first but it's close enough. Especially for the short turn around of development.
Cannot WAIT for Skyoshock.