Well I'm a big fan of the setting for one and LotRO does a pretty solid job of staying faithful to that setting.
The game as a whole is a themepark MMOG that is based on questing, like WoW. The differences are the quests are generally better, and there are story-lines based on race and quest as well as the events from the setting (the fellowship, etc.)
Also the community is on the whole beyond better. I'm on an RP server (Landroval) and it's like night and day. The general channel is filled with intelligent discussion, people who ask questions, are actually answered, not screamed at, etc.
It's an all around solid MMOG, a rarity in the genre (which is crazy really), and quite a lot of fun. If your a fan of the setting or even simply looking for a well rounded MMOG with a good community, it's worth a look.