EXCELLENT!
counter strike source is similar to the original cs but has many improvements most noticably the new source graphics engine that breathes life into a already great game.
The ragdoll physics of cs s are excellent making it feel like you really killed that person. The maps have more life in them as well with the new engine.
More detail is noticeable in all graphic aspects from the guns having scratches on them to the backgrounds of the maps for example de_dust seeing a few buildings and desert around the map in the distance.
cs:s is a very polished game and if u can bear using steam it is well worth playing.