what's there is good
The game that's there is really good. The scoring system was interesting. I do think it could have been much better if it had had a little more "beef".
For example, there could have been different kinds of attacks (non-homing rockets, cluster bombs, double shots, triple shots, a spread of (non-homing) bullets that goes to all sides). Also, the game could have had more stages, letting you finish each (but the last) after some time by doing something special and then moving on to the next stage. Also, you could have gotten upgrades (in speed and such). Also, this is the typical game to include temporary power-ups (invulnerability, +1 guy, +speed, shrink, etc) .
Anyway, I could ramble on, but I guess you get the point: there's just very little in it - that could have been much much better.