I've been playing Morrowind for a few days now.
Graphically, it's amazing. The water effects are especially good - they are probably the first good use of a GF3 (or 4, of course) that I have seen in an actual game. Of course, the game cripples my system - I have an Athlon at 1.4, a GF3, and 256 mb RAM and the game is playable, but chops quite a bit in busy areas.
If you like massively open and non-linear games, then you will like Morrowind. There is a main plot thread, but at any time you are free to go off on tangents and explore any of the hundreds of side quests that exist.
Personally, I find the game a bit overwhelming - I feel like if I sat down with it and spent a good deal of time with it I would love it - but I simply don't have the time to devote to it to really explore the world. As it is, I can't shake the constant feeling that I'm missing something in the game, as there are hundreds of NPCs and miles of terrain to explore.
My overall verdict is still pending. If you like huge, open-ended fantasy RPGs, you will love Morrowind.
<b>1.4 Ghz AMD T-Bird underclocked to 1 Ghz...just to be safe!</b>