I play CS:S more than CS 1.6, but I like 1.6 better. I only play Source more because more people play it here at Purdue than 1.6.
Oh yes, you must also check out Goldeneye: Source
http://www.goldeneyesource.com/
you can download it here:
http://mods.moddb.com/4506/goldeneye-source/
Yeah, you remember Goldeneye for N64. They're working on it using the Source Engine. Only multiplayer is up right now, but they are only at Alpha 1.1 right now. You should get it before it gets shut down (perhaps copyright issues).