It may be addictive, but Everquest II is still a great MMORPG, and one of the best out there for sure.
I've been to WoW, LotRO, EVE Online, Vanguard, SWG, and several others, but there's just something about Everquest that I keep coming back for.
I think one of the main reasons is SOE's content additions. Of all the MMO's I've seen, content is most regularly updated and added in this game. From the four expansions to the adventure packs, and now to the free downloadable game data, it looks like there will still be more and more content coming.
They've also done a fairly good job balancing the classes, and for the most part, it's not about a certain class being better than another, but a gamer being better than another in PvP.
The quests are numerous, the Alternate Advancement lines give you something to strive for, and the Epic Weapon quests, the big mobs, the instances, and the PvP action make EQ worth checking out for sure. I can't think of any other ways to detail my recommendation other than to say I keep coming back.
As always, check out the free trial. If you're looking for something you can really sink your teeth into and get a lot of value out of for the $14.95 a month, and you are a fan of quests and fantasy, then this is your game.