Loved Bioshock 2, but I fully acknowledge it has its share of issues. For one thing, the story is short, which was to be expected considering it was a much more structured narrative. The game told you what you were going to do, you do it, end; it didn't over stay its welcome by dragging on, but I do wish it had been a bit longer. The characters were also an issue, but I wouldn't call them "bad." Tenenbaum showed up for a brief stint and then vanishes, only to be replaced by Sinclair. Sinclair I liked, don't get me wrong, but he was no Atlas, nor was Lamb a suitable successor to Ryan. I enjoyed these characters, but they simply didn't click for me as readily as those of the first. Other than that, loved the single player.
Multiplayer bothers me. A lot. It may just be due to the fact that there are online trophies that are pissing me off since I really did plan on getting this game's Platinum trophy, but not it will take much longer to do so. Multiplayer is different, but it could have used some extra work on it. For a first attempt at a Bioshock multiplayer experience it should be commended, but that being said, scrap it or give it a complete over haul for Bio3 if it should exist.