Our first glimpses of Counter-Strike: Global Offensive haven't been particularly encouraging. Early footage of the game looked a little lo-fi for a modern title, but Rock, Paper, Shotgun has some promising new screenshots. Although the visuals aren't stunning, they do look like a definite upgrade over Counter-Strike Source. You can see all of the screenshots in the gallery at the bottom of this post.
RPS also reports that CS: GO will include new Arsenal modes based on the Gun Game mod for Counter-Strike. Gun Game replaces the monetary system with a guns-for-kills model that starts everyone out with a basic pistol. Players are rewarded with new weapons for kills, which nicely matches Valve's desire to expand on the number of guns commonly used on Counter-Strike servers.
Valve has a history of hiring mod developers, and it's working directly with the Gun Game creators to flesh out the new Arsenal modes. My Counter-Strike addiction ended long before the Gun Game mod became popular, but it sounds like a fun twist on the core gameplay.