Yes. I remember trying to go back and being pretty depressed when I saw Felucca =(

I played UO from release untill around 2000, I quit shortly after Trammel was introduced and moved on to Everquest. UO was a great game for its time, a lot of it was just how new everything was. The whole concept of the MMORPG was brand new at the time (excluding MUDs). This makes it very easy to confuse nostalgia with a truely good feature =)

Most people think of open pvp and full loot and don't understand the way UO worked. UO was not item based at all, you would often have 5 or 10 extra sets of gear sitting in your house or the bank. Although it was annoying, getting PK'd was not the end of the world. I can see how people from WOW or most other MMO's being played today could misunderstand this. If you lost your sets of epics in WOW you'd probably just quit

Less restrictions on players. Players were given a lot more freedom than they are in more current MMO's. In UO, you could attack anyone, anywhere and loot their whole corpse. You could place houses wherever you wanted, even in a way that would block off content for other players.

Anyways, MMO's since then have realized that you have to restrict a player's ability to impact another player's level of enjoyment. As is true with most of the internet, theres always some guy who'd love to ruin your day

It really depends on the era of UO that you're talking about. Early UO is pretty uncomparable to any MMO that is out/in development.