I'm not a fan of the game. The overall interface was too simplistic, as was the ground and space combat, as mentioned already. From what I recall, there was no real open-ended mode -- either you fought pre-configured space battles or campaigns that are limited in scope. (I recall some ridiculous liberties they took with the plots in their campaign, like Captain Antilles flying a near-invulnerable Corellian Corvette and knocking out a whole fleet of Star Destroyers in dock.) There are other limitations to the game - like having to jump from planet-to-planet, Wing Commander style, to reach your objective, as opposed to make a singe hyperspace jump, Star Wars style.
If you want to play a great Star Wars RTS, I recommend Rebellion. It has a huge scope, variety of missions, and has a very dedicated fanbase and modding community. I thought Empire at War would be a spiritual successor, but was sorely disappointed.
I got EaW a few years back, at a discounted price, so I can imagine it's pretty cheap today. I never got a chance (or didn't want) to play the expansion, but I here it's a proper expansion and the three-sided warfare can make interesting combinations. If you are a Star Wars fan, and an RTS fan, and can find the two-pack game/expansion for under $20, it's probably worth it.