On the surface, Warcraft 3 contains the same RTS that Blizzard is famous for, with other well-known Blizzard features thrown in. The feel and strategies are Warcraft 2, the races have the variety of Starcraft, and the game play has RPG elements as well as the collectable item aspect of Diablo. You can really see bits and pieces of the different games in Warcraft 3. For starters, the camera angle resembles Diablo's isometric view more than Warcraft's or Starcraft's top-view. This adds to the 3D aspect to the game.
Heroes can carry items, and give off auras to surrounding units.
Humans seem to again be decently strong and well-rounded, but somewhat defensive like the generic paladin. Orcs are heavy into melee and very aggressive. We didn't see much of the other races, but we can probably guess that the Undead center on death, life stealing and raising dead corpses while Demons are probably just pure evil. Unlike Starcraft, Warcraft 3 has more of an emphasis on unit quality instead of unit quantity. Climbing the ladder to reach more powerful units hasn't slowed.