This is so Underrated it's not even funny, far by my most favorite game.
Other than that the game is flawless. The gameplay has been drastically improved. But what really got me is the multiplayer. It is surprisingly very fun. It feels a little chaotic like tf2. It's similar to old school pc games, hoping for a fun and lasting experience than a super hard and skilled multiplayer. The tonics and plasmids give it also a little bit of modern warfare. But of course all bs1 fan care about the single player. The single player isn't as good as the tsunami of the original game, but is still miles better than MF2 and halo's story and a-lot of other games.
Definite buy, no rentals. You won't regret it.