LOVE this concept a lot as someone really into space and gravity physics. The meteors didn't really make sense in their placement and felt unfairly used against me. I feel as though the meteors should have been changing trajectory in accordance with the gravitational changes, which would have been REALLY CREATIVE and useful for showing how your changes affect the physics in real time! Just putting them in the background for the visual flavor instead of making them objects that hurt you would have been excellent if used in that way.
I also couldn't for the life of me actually figure out how to make gravity work for me, and felt more as if futzing around blindly was doing me more good than trying to think logically about how the gravity actually might conceivably work. I also wondered what it meant when the planetary bodies started spinning after being hit. I had a feeling it was changing things in some manner, but it wasn't altogether clear what purpose it served other than to provide visual interest.
I consider it a great game in concept, if only the physics were more clear-cut in how they worked. Love the title screen a lot, also!