So far, so good. I was thinking it was too easy at first (especially as I am generally not any good at FPS, but was doing well). However, I am stuck at the end of I think part 3. Just too many portals... I'll play more tomorrow.
Some of the graphics are fairly good like the water effects, but the levels are a little too linear so far (at least you don't have to worry about getting lost). However, I do agree some do seem kind of bland. Not sure about your complaints about controls, but I haven't really wanted to lean out of cover yet. The levels are a little plain, and only a few things are destructible, which should be nothing special these days.
I'll definitely keep my copy, but I rarely return copies. Not a 10, but a solid 8 if not 9 assuming the multi-player is good (which I haven't tried yet). I can understand why some might give it a 7, but anything lower and people are likely showing a bias.