It was amazing in it's heyday.
Has any other multiplayer game since then persisted items in the game-world (i.e. dropped items and such)? I miss that. And the housing was a lot of fun.
UO was the first "massive" online game I'd ever played. Getting murdered and running around as a ghost was fun the first few times.
http://www.havenandhearth.com/ has a similar feel with less players. Plenty of housing and PKing though.