Summary
Good for wargamers, but it's lost it's charm.
The Good
Empire II was obviously designed with hardcore wargamers in mind. It has numerous rules for terrain, fatigue, moral, and even weather. Plus, you can create your own maps, scenarios, and even units! In other words, it's highly detailed and very customizable.
The Bad
Although it's part of the Empire line, it's lost much of the charm. I think this is mainly because of the lack of exploration required. In Empire and Empire Deluxe, the fact that you have to explore the planet/area you're conquering plays a big part in the game. That's lacking from this version. You always see the complete map, it's just a matter of being in range of sight of enemy units.
The Bottom Line
If you're an avid wargamer, you'll probably enjoy it. However, if you've heard great things about Empire and Empire Deluxe and think this will make an acceptable substitute, think again.