If you like Counter Strike with lots of hollywood effects, get FEAR Combat.
Where FEAR shines is in the presentation. Lighting effects, debris, smoke, bullet streams, shrapnel, blast waves, flames, and good texture damage marks all make the firefights extra exciting. Yes a decent computer is required (more than decent) to get the max out of it but even at lower rezes you can get some great visuals.
Gameplay is solid and fair, within a few games you will find the weapons well balanced and easy to use. FEAR never feels cheap or leaves you thinking your getting scammed by some uberplayer. Player limit is 16 and that is more than enough to feel like part of a solid battle.
It is free, fun and the best free MP on the market.