It's by far the best fucking FPS I'ved played to date, and I think everyone should buy it. Blackhawk down is pretty fun too, but Far Cry fucking owns.
Fuck Doom 3, it didn't take me very long to figure out how badly that game would suck in multi-player, and I didn't even play it in Multi-player, I just know it would suck. In fact, I think I'd rather play old doom in multi-player, then in the P.O.S. overly critical lighting effects in that game.
Far cry also has an awesome 3d map editor, which makes it easy to make your own mods, and map files.
Make sure if you intend on buying Doom 3 just download it off the net with all of the cracks, since ID Software doesn't deserve the money for it.
However, do your part on the gaming community and buy Far Cry. I didn't, but it's worth buying.