Really good
I really liked this game. The gameplay is fun and the weapons are also balanced & varied in a good way. I never felt that any of them were pointless, wich is common in this type of games. However there's a little problem; the money earning. I felt that the money was gained too easily and the stuff was too cheap. There would be no point in adding a star to a weapon when you could just play another level and will have enough money for a new one. You should've made the jump from one weapon to another more distanced, so that the upgrades would come in play. Also making the game longer, so that you could actually see atleast one of them getting full stars.
Another thing that brought it down (altough only slightly), was the enemy design. They looked really boring, with ugly single-color clothes resembling those of an astronaut or something. Nothing that would make the game boring by itself but it could definately have added some graphical enjoyment. The background on the other hand was pretty great, having that Soviet feel to it.
Last but not least, the music. It was a good song and added to the overall enjoyment.