It's nice, but...
The health bonus give far too little life compared to what one loses during the game. Another issue is that the upgrades really felt like they made little to no difference, and upgrades is something I'm very into. On the other hand, I had no issue with lots of enemies popping up, just that it felt like the mech wasn't made from a very durable allow ;)
I did enjoy the artwork, as well the combos, but I felt like there should be a few more sfx going around, I like listening guns firing AND hitting the target :)
Overall an enjoyable game, though some refinement could be done.