Gamespot have whizzed up their impressions of the final build of CS: Source.
Here's a some of it:

"CS: Source comes with nine different maps, but again, none of these will be new to longtime players. It's still extremely fun to see old favorites such as Dust, Office, Aztec, Italy, and Cobble in a brand-new light, thanks to the improved graphics and detail afforded by the Source engine. The most obvious change is the inclusion of more detailed skyboxes that actually render the tops of buildings. On Aztec, for example, you'll actually see the tops of the pyramids that you're fighting in, and if you can find a moment to stop and look around, it feels more like you're actually in the center of a large archaeological site. Other outdoor maps, such as Dust2, also benefit greatly from the improved detail.

Want to read on? Don't forget to check out the whole impressions article.