I like the music. The graphics are simple but fitting. The little text when mousing over the robots is cute. The acceleration and fall of the spacecraft, in spite of the basic graphics, is quite effective--I actually felt a little motion sickness each time I fell from a great height. :)
Ultimately, the gameplay doesn't have all that much variety. The upgrade system seems interesting, but all we can do is just rise vertically into the sky. It might have been more interesting if there were steering around obstacles, dealing with damage, etc.