Not particularly good or bad.
With those as benchmarks for all RTS games, this one was a pretty solid mediocre, and not much more.
I think the two things that turned me away from the game the most was the strange unit design, and the Heroic Point system (I'm sure that's not the real name), that seemed, at best, ambiguously implemented into the gameplay.
The units neither looked nor behaved like their movie/book counterparts for the most part, and great liberties were taken in most areas. I'm generally and marginally ok with that except they took it a little too far, and in strange directions with this game. The best example I can fish out of my foggy memory of this average RTS was the Urak'hai, which in the books/movies were larger than normal orc mixes that were mainly proficient in tearing things up via melee combat. Well in this game, they were purely archers. Yeah. It would only be fair, however, to say that some units were pretty cool. The Witch King, for example, could summon several powerful Ring Wraiths to run around, and it was pretty cool to feel in charge of that action.
As to the aforementioned point system, it was basically an indicator at the bottom of the screen that filled up with White or Red looking eye icons (Depending on if you were playing as the Armys of the Free People or that of Mordor), that would allow you to purchase things not available with mere gold/lumber type resources. Some of these things were upgrades for hero units like Sting for Frodo, etc. However these were awarded at strange intervals, and kind of felt like a gimmick just to add a bit of flavor to the game. It didn't really work.
All of that criticism being said, as far as the game mechanics went it wasn't an uncomfortable or poorly made RTS game in general. I did have a bit of fun going through the campaigns, but I don't think I carried it much past that.