How is this game "unstable?"
This is truly a game built on city building. You can pick scenarios that are nothing but building. It's true that the battling is more of a sideline - I felt like I was playing "Stronghold." If you've ever played that game, Imperium Romanum will seem familiar. Especially with the mining and wall building.
The graphics are pretty decent, but you can't pull the camera back far enough. I would like to have been able to see the city from more of a bird's eye view. You could get a better idea of how you want your city to lay out.
At $40.00 it's a little high priced in my opinion. I'm really not getting the feel that there's a whole lot of new and interesting material here. But I totally disagree with the Gamespot review. My experience is that this game if very stable. I have a XFX GeForce 7950 GT and an AMD 4200+ with 2GB RAM. Not that great of a system for today's games, but Imperium Romanum runs very well with my rig.
Bottom line, if you like city building, Rome Style, check this one out. Don't believe the Gamespot review about all the instability. And the graphics are quite nice.