Armada is basically Diablo fused with Asteroids, simply put. This is, for the most part, a very excellent meld, and is handled well by the developers.
On the down side, both Diablo and Asteroids are quite repetetive games, and this carries through to Armada intact. If long cruises through space occastionally blasting aliens doesn't appeal to you, you may find this game long-winded.
In the end though, it's a lot of fun for either a single player or up to four, as long as you've got some attention span. Rewards in the form of super-cool weapons and ship upgrades do come along, and there's a feeling of adventure that gets this game a thumbs up from me.