DD is a 2D game with an isometric camera view, like D2, and also has similar movement and combat controls. However, the story, quests, dialogs, humour, etc give it a much different atmosphere, IMNSHO.
FWIW, I started playing D2, got bored, started again with the expansion, got bored again and never finished it; DD I've finished and played a fair bit on top of that (though graphics are not terribly important for me).
