The archer: no clue, only used him in the tutorial, where I had to.
The mage: the most powerful class. In one mission where I had to defend a spot, I went with the warrior. It didn't work so well, but when I tried the mage... well I went through the whole game only with the mage afterwards. He has healing, a spell-projectile shield, fire wall, chain-lighting and physical-staff-in-the-head-bonk attacks. And as Baku would say, the greatest class in the game would be Gandalf.
Heroes: They are more-powerful versions of the above only with one extra-damage-doing-thingy (Aragorn has the army of the dead).
Well, I haven't played the game in multiplayer, but it doesn't really look balanced to me. The campaigns are short. After doing the good campaign, comes the evil one. Here, I was expecting (as always) a plot with a some side-turns or whatnot, but instead in every mission you have to kill another one of the fellowship's
The sound is pretty neat, well it's the LotR OST which I listen tosanyway when i play Oblivion/Morrowind. The graphics look old and dusty, but sometimes they can catch your eye.
the bad: no saving (I know it's a multyplayer based game, but they could've made a quicksave), crappy balancing (my opinion), faded graphics
the good: it ends quickly, the soundtrack