After about 3 hours of play time, I would say that Empire at War is good, but not great enough to warrant my $50.
The space battles are great, with nice visuals and intense fighting, but the land engagements are very underwhelming. There aren't too many units to fight with, and the maps themselves are constricted mazes with few tactical features. The indigenous populations add some variety, but the AI is weak overall.
The grand strategy portion is very well done, but you'll probably want to skip right to the galactic conquest mode because the campaign is pretty boring and restrictive. The game is loads of fun when you have complete
Rebellion - style freedom to conquer planets, retreat from tough battles, and use heroes to gain an advantage.
Overall, I'd say that the game deserves a solid 8.5/10. The sum of its parts is good enough to warrant a purchase.
Plus, Kyle Katarn's a hero for the Rebellion, so that counts for bonus points.

You could no more evade my wrath than you could your own shadow.