LOTRO is a very player friendly and beautiful looking MMO. I've been playing almost a year now and have a life time sub which will soon pay itself off.
Quests:
The game is causal friendly and there are a lot of solo quests. There are quest lines and instances that require 6 man fellowships but they can be bypassed. It is possible to get to lvl 60 doing nothing but solo quests if that is your thing. There are also 12/24 man raids if that is your thing which are awesome but not the main focus of the game.
Classes:
Burgler: debuffer, dps, crowd control
Champion: aoe dps, offtank
Lore Master: crowd control, aoe, debuf removal, pet
Captain: offtank, buffer, pet, support healer
Guardian: main tank, dps
Hunter: single target dps nuker, travel utility powers.
Rune Keeper: dot nuker, healer
Warden: offtank, dps
Minstrel: main healer, support buffer, support dps
Most played classes are Hunters and Champions. (Everyone wants to be a Legolas/Aragorn)
Most challenging classes are LM and Captains. They are a sort of do it all character so juggling around their abilities is a challenge but very rewarding.
Slowest character to level is the Minstrel. Healer class takes longer to kill things but much wanted in groups.
Look me up any time. I play on the Landroval server (unofficial role playing server) Rustican.