Polished shooter and tons of fun!
It's a pretty simple isometric shooter, but the sound effects are great and the weapon variety works flawlessly. Just like some of its better predecessors, I kept thinking "just one more level" and then I'd look up at the clock and five hours would have passed...
Put simply, if you can pick this up for under $10, it's a terrific buy -- and better than a lot of the crap put out by the big studios these days. The only con thus far is that I'm guessing the replay-ability is going to be pretty limited. It's also gotten somewhat less challenging once I learned how to effectively use each weapon (and their respective upgrades)!
Regardless, Gamespot's rating is way too low!!!