There were levels where you would go into nearly the same room (with small variations) to kill the exact same number and type of enemies.

That was shoehorned into the game last-minute to increase the play time. Lame but they had to get it out by launch.

I was underwhelmed by the whole thing

Yeah if you play it now it seems basic. But that’s like listening to the Beatles now and saying they aren’t very interesting, when everything current is based on what they did.