The first thing to be said for the Fortress is: It's not THAT bad! The Fortress takes a lot of heat for being one of the weaker towns in Heroes 3, but that doesn't mean you can't win with one. Personally, I think Fortresses have some of the most interesting units in the game, and are a lot of fun to play.
The Fortress
Fortress Units
Fortress Heroes
Fortress Buildings
Fortress Magic
Fortress Strategy