they are pretty cool, I beat my roommates copy of the two towers before he did (infact he sold it before he could beat it cause hes a sucker) its a pretty cool game, although I haven't played any of the other ones. My main gripe with the game is the camera angles, they will have you shooting arrows at enemies that aren't even on screen, and sometimes even slashing them and shit. it gets to be quite annoying. you don't do anything in the game beyond the hack and slash thing, which can get repetitive. The game moves from FMVs to in game sequences very smoothly.
For $20, personally I would let it pass, but thats only because I've already beaten it. Pay more money for ROTK, naw, It doesn't interest me enough.
Its a cool thing to have for lord of the rings fans, although it doesn't have much replay value.