It was okay.
Movement mechanics are nice and smooth. Movement was a little bit slow for my tastes, but overall it was it wasn't bad at all. Sometimes the bouncing on the next platform down was over exaggerated, but once again it wasn't really a big problem.
The shooting was a bit awkward because there were so many enemies to shoot at which move up and back and forth at the same time. There were also a lot of enemies shooting at me, and the health restoring items were quite sparse. This causes many unneeded deaths.
On another note: You might want to take a look at the respawning mechanics: I ended up dying and respawning on a long platform almost completely at the top. I couldn't move to the edge fast enough, and automatically lost another life.
The music is really nice sounding, but repetitive. Not much I can say about it.
Overall, it was a good try - nothing entirely too special but nowhere near bad. I'm sure if you put your mind to it, you'll be able to do much better next time around as well.