After witnessing the deluge of advertising (including the "Making the Game" special on MTV) and seemingly universal critical praise for the console version of the game, I purchased the PC version expecting to play the same thing.
The graphics are horrible (the Unreal engine is capable of ten times more; yet half the cutscenes are prerendered anyway by what seems to be an old, half-broken Nintendo 64), the same five enemy characters are re-used ad nauseam (and use the same taunt dialogue again and again), and the controls are non-standard and generally annoyingly difficult to use.
Most of all, the free-roaming environments and non-linear gaming so touted in the promotional materials _are not part of this game._ Even though the structure of the PC version seems designed for a console ("save points" instead of save-anywhere design; only one game can be saved at a time) it lacks any of the special features advertised for the console versions.
The Unreal engine can blow away even the Xbox's best efforts, and it's a shame that its power wasn't harnessed. The biggest shame, however, is that Activision has duped gamers into purchasing a totally linear, almost thoroughly unenjoyable product that is wholly different from the one that has been advertised excessively in the past weeks. I feel disappointed and cheated, and I hope I can get my money back. :-P
Sorry for the cross-posts.