UO Consists of 4 things now:
1 - IDOC watching as 5-6 houses fall per day (18x18s)
2 - About 10 people yew gate fighting and yelling obsinities at each other in chat
3 - Navery in the new dungeon that drops new apron very rarely and has 15 min spawn timer.
4 - Can't think of a 4th....
UO is as dead as I've ever seen it. I'm on GL and it almost scares me when I come across someone else in game.
Hmm, maybe that is just Great Lakes...
I play on Atlantic (just came back after not playing for a number of years) and run across people frequently, sometimes out in the middle of nowhere. I generally find large congretations of people in Luna and New Haven. Smaller groups I find at Brit and occasionally other banks. The Abyss and Underworld have players in them consistently, and I even run across other players semi-often in the regular trammel dungeons.
I am part of the RP community on Atlantic, so one of the fun things to do, as you might guess, is RP if you're into it. It seems pretty healthy here thus far, and the community is sizable enough. Hell, I have even met some new people and made some new friends recently.
IDOC camping does seem fairly popular, but then again, it always was. It means free loot, so of course people will want to do it!
I can't speak much on the PvP in Felluca aspect of things as I haven't been there, but Yew gate fighting seems popular. There seems to be a fair amount of PvP (or ganking at times, depending on how you look at it) at Champ spawns as well.
My advice for having fun in UO now is this: Find a new group of friends and just do whatever tickles your fancy. Just romping through the Abyss with a few guildies is enough to be entertaining. Even better if you get a bigger group and take on the Slasher of the Veil
Anyway, if you find your way over to Atlantic, let me know

Have fun!