Mediocre
Fun at first. Then it drags on. And on. And on. Lots of lots of levels with very little change in the action. The option of buying new weapons make an already easy game ungodly easy. And then you have the nerve to make me start over at the very last level, so I don't get to see the end, after slugging it through all that way? Tsk tsk.
I'm highly tempted to blam it just because of that. That's not challenge, that's just frustrating. Frustrating is not fun. Luckily, I realize it wasn't a bad game, all told, and will score it appropriately.