Yep, I finished BioShock 2. Really a great game. Though it had the same awkwardness that BioShock 1 had. They kinda just throw you into the story... And I like it like that...
You see, in Half Life 2, you have to go around learning plot developments and working your way around the world, figuring out your situation. Stuff like that. But in BioShock, in less then ten minutes you have a pipe wrench and zapping splicers. BioShock 2 only about five minutes and you get your first kill of the game. I really don't enjoy slow start-ups like that. I'm a instant gratification type of guy.
I've only tried the Multilayer once, and I got my ass kicked. Over and over. Had lag spikes and lost my connection. But I killed one person!
Also, a little spoiler here for ya, Touch the 'Unstable Teleportation Plasmid' every time you see it. It'll be worth it. ;)