I just bought this game.
Let me say after playing a few games CS:S feels quite dated.
In fact, I am surprised this came out only 9 months before Battlefield 2. It feels way older than that.
It may LOOK dated, but it definitely doesn't FEEL dated. Considering all the mods and different "game modes" there are to play, it provides a far fuller experience than BF2, COD4, etc. I find that the weapons feel far more accurate and powerful than the said games as well. When I'm firing an AK47, the combination of the gun barking, the recoil, and the damage it does to opponents makes me feel like I'm carrying around something to be reckoned with. It's still far from realistic (if it was, it'd be quite a boring
game), but much better than the 15 bullets it takes to kill someone in many other games.