As Brian said, it's similar to WoW, you have classes and quests and progression in a similar manner. But it's really its own game. It's based on the books, not the movies, and it makes great use of the license. The world is huge and absolutely gorgeous. The graphics are very nice and quite realistic, the player base is typically more helpful than in WoW, and the game has a much greater storytelling focus than WoW does.

In LotRO, you have two distinct types of quests. There are your normal quests that you pick up and go do, regular quest chains and one-off quests and such, very similar to WoW. But then there's the epic quest line. This is the main story quest line, and it features solo instances, scripted events, and every once in a while a group quest. The story takes place at the same time as Frodo is going to Rivendell, but is a parallel tale that takes you across the northwest corner of Middle-Earth, fighting back the evils of Angmar and the gathering forces of darkness so that Gandalf and the Fellowship can do their thing.

The game features free major content updates every two to three months, with a paid ten-level expansion every year, year and a half.

It's not quite as smooth and easy as WoW is, but the storytelling is much better, the world is very well done and takes itself seriously, there are unique game mechanics at play that set it apart somewhat, and it's a great game if you want something familiar but new and fun and interesting. I haven't regretted trying it.

The game is primarily PvE-centric. It doesn't have free for all PvP available. What it has is monster play, where you can take control of upgradeable monsters and fight real players in a PvP zone. If you want a deep, focused PvP experience, it's not the game for you.

There's a 10-day free trial available. Also, if you download it online, you get the game plus the Mines of Moria expansion plus a free month of gameplay for $10.