Everyone should know this game — especially know that GOG has recompiled it to update the graphics settings. The adventure part is good and the universe is awesome. The action system is of course a bit outdated (the stealth system especially can a bit clumsy by today's standards, often you're better off rushing in) but still quite enjoyable, and for a 90's 3D game that's a feat. It's a bit short too, like all good games. :-)
I remember that I loved this when I was a kid and I was very happy to play it again. The gameplay is original and very interesting, with all the races, heroes and the experience system. Nevertheless, I also found it quite unpolished as there are a number of things that don't work well. Among other things, most magic spells are essentially unreachable because of their crazy development times, moving throughout the map also takes too much time (and there are no shortcuts), the way conquering other races works isn't really enjoyable, some tactics/units/items are unbalanced. The game misses a decent tutorial, and the main campaign scenario isn't very interesting because the AI is abolutely terrible at strategy. Overall I liked discovering the gameplay very much, but the game soon started to be tiresome. I'd only recommend this game for people who played it in their youth and for hardcore turn-based strategy fans.