First off I'm a massive Resident Evil fan and have been since the original release in the mid 90's.
There are lots of things wrong with this game, the AI is shockingly bad in the single player missions and the game is very short. ,some of the controls are a bit poor, most noticably no quick turn around.
But, with all that said I've became quite addicted to the online modes. Obviously we'll need to wait till Resident Evil 6 to get a better quality game with a Mercenaries mode but ORC is still a pretty good game, if you can forgive its faults.