I thought Medal of Honor was excellent.  Although some levels were too arcade like, such as the Tiger Tank and Jeep levels, it was a good learning experience for me, as I don't tend to take a whole lot of interest in the terrestial war, though that's changing now.  As a sidenote, I think it had some of the best music ever, at least in a game, especially the file "mus_TigerTank_01a.mp3".  In fact, it's in my Winamp playlist right now.

The thing I liked best about it, was it conveyed the atmosphere of war respectively, except in those arcade levels, of course.  The Normandy mission was a real sobering experience.