3 months ago I was very interested. After the demo was released it felt like just more of the same.
I have read the latest update has caused CD and Mod issues. Oh well. I don't have a compelling reason to buy it.
With HL2 and Call of Duty coming out soon, there is no reason to.
If you haven't seen some of the mods for Call of Duty Demo check here. Highly Modable even in demo form.
http://www.modtheater.com/forum/forumdisplay.php?forumid=72richcz3