One of the best shooters, next to the Halos, I've played since GoldenEye for N64.
This game has got to be one of the bests I've played in a LONG time.
Halo is great, but, this game is amazing.
The Deathmatch modes, when you get into a good game, it's non-stop killing. You spawn, you kill, you take 2 steps, you die, you respawn, you kill, and so on. It's non-stop. You'll never know when an enemy is gunna find you, so, hide.
The graphics in this game are absolutely perfect.
The character models when speaking move like a real human, and show emotion. In other games, the models just stand there, talk, and walk, and show no emotion for those around, acting as if they aren't there. But, when you look at someone in this game, they will occasionally look back and things like that.
Sound. Well, it's perfect too. When in City 17 you can hear Combine vehicles and things moving about the streets. When toward the end of the game, you can hear gun fire from places. Yells and ect.
I'd recommend playing this game, without looking at anything, just playing. Then, playing a second time to observe the amazing things Valve has done to make this game look great.