Weak, repetitive and uninspiring.
The game's real time nature squanders much of its appeal. Essentially, there are two phases of play -- a galactic phase, in which you coordinate assaults on planets and build structures, and an assault phase, in which you lead air or space battles directly.
The galactic phase is incompetently designed, however, because the action never really stops. When you control several planets, juggling between various upgrades and obscure buildings while managing fleet movements becomes virtually impossible. All the more frustrating is that the computer (whose AI also has noticable shortcomings, especially in noticing your weakest planets) has no such coordination problem. The designers should have taken a page from Civilization IV's playbook and made a competent turn-based segment here instead of a frustrating real-time mode.
The space battles are repetitive but at least look pleasant. The player can call in reinforcements but strangely cannot choose his initial starting forces (if you send in 20 units, the game might randomly pick 10; as they die, you can gradually draw reinforcements from the 10 left in reserve). The AI here is competent but the only strategy is targeting hardpoints on enemy ships, which is not terribly engaging since your choice ultimately does not effect much. Simply focus-fire, and repeat.
The ground battles are even more terribly repetitive. The AI is weaker here as well. The only novelty is the coolness of using the Emperor to decimate an enemy infantry division. But you will simply not want to use this mode or the space modemore than 5-10 times, which is pretty damning since they make up 1/2 of the gameplay; and, as mentioned, the galactic mode is designed poorly as well.
The designers had a good idea but their game has virtually no replay value. You'll probably put it away in a few nights.