I finished this a couple of days ago too, really great game - made my xbox purchase worthwhile :).
Really a good mix of missions, and I can't wait for some more levels. Doing extraction on the last mission was a killer for me, I had 4 bullets and was pretty low on health - found a way to sneak...
Interesting, the Gamespot reviewer seemed to complain a lot about the difficulty in the review rather than any major flaws. This should be good flamewar material (and already is from reading a couple of other forums :)) in the making! I won't be picking this up right away in any case, too many...