Yah Siren was really difficult. That's one reason I think some people were caught off gaurd somewhat with the game, you almost go in expected enemy AI in survival horror games to be dumb, and then all of a sudden you've got some of the best AI in any game coming at you.
I don't think enough people gave the game a chance. It's easily the most creative survival horror game to come out in a long time, maybe the most creative since the original SH. It's gameplay is pretty decent too to go along with a great plot.