Great production values and great licensing of the Lord of the Rings movies.
It had more depth than it appears. There were four asymmetric factions here: Mordor, Isengard, Gondor, and Rohan.
The core idea of the game is that your initial base only has limited room for structures, so you must make an initial choice of strategy that you are going to attempt, and then you need to come out and expand by conquering other base locations in the map before your opponents do.
Every faction has several possible strategies, chosen by the kind of resource buildings you decide to create and the production facilities you raise.
This game discourages sending lots of units to their death, since killing units grants the player unlockable and thematic powers and effects during battle that go from summoning allies, making the sun raise and stunning your opponents, calling the Eagles, or bringing up the Balrog.
Each faction had also unique heroes from the movies that you had to level up in battle to unlock more powerful abilities. These heroes could change the course of the game. Among them there all the fellowship members, Saruman, Gollum, or the winged nazgûl.
The two single player campaigns (good and evil) were great, with a full map of Middle Earth were you can capture regions to get stronger, or go straight for the story.
Then, there were lots of multiplayer or solo skirmish maps, and it came with a map editor to make your own.
I spent lots of time making maps, and was part of the awesome modding community that flourished for this game.
The sequel, added a multiplayer conquest mode, which was great. But screwed other stuff, like amalgamating Rohan and Gondor in a single faction, replacing the strategic base building system with a "free-build anywhere" one that, while it sounds better, it robs of much of the interesting decisions from the original. Also added Goblins, Dwarves, and Elves as factions, which is always good, but suffered a bit of generic fantasy design.