Good review. I have had the game a day now and like you only been playing in Hardcore matches which seem well balanced and full at the moment.
I have FX4170- 4.5Ghz GTX 460 1GB O/C 800. Runs fine but at lower res and medium graphics, started in 1680 x 1050 as seemed jerky. Playing at same resolution as COD4 (1280 x 1024) and graphics look great, yes better single player but multiplayer is good, well thought out menus, graphics, and maps, huge maps with lots of hiding places so usual slaughtering on occasion when you first play. Three classes of soldier then so many point to spend on guns and attachments in that class, not hard ranking up though to unlock more. The expensive ones are not always the best.
It's no COD4, more like MW2 and Black Ops, console port but done well. My son plays with the xbox360 controller plugged into PC and is good. I prefer the keyboard/mouse, seems to suit both types of players.
Recommend for a bit of fun.