The music is GORGEOUS. CD based, hell, I'd cut me a copy just to listen to in the car.
The graphics are quite attractive.
I think the spell system is an improvement over the original (spell points instead of memorization). And certainly the wide range of abilities now available to characters is great fun.
I think the campaigns are EXCELLENT. In fact, I played them to the exclusion of the single shot scenarios. During a lull in work I got so hooked on this game that I spent 10 days straight, from the time I got up to the time I went to bed just beating the campaigns.
The strategy becomes early apparent. Build up one hero to disgusting levels, lump him with all your most powerful monsters and stomp some computer ass.
Other than that, flawless. I prefer this game to Heroes III.
The Bottom Line
One of the all time best fantasy strategy games.