While a lot of people think this is the 'cartoony' Diablo, I personally found it to be my favorite version, and one I kept going back to again and again. Something about the story, the characters, and the way it all looked (I actually liked how 'colorful' it all was compared to others, and saw it as a natural evolution of the series from Diablo I & II). The seasons really added something cool IMO and I found myself trying a new class every time to just keep things fresh.
It's not perfect, but adding it to GOG would give it an offline mode which the game sorely needed.