Good. I liked it.
I liked it and I beat it. I realised though that one of your weapons is far too godlike.. The laser beam one. lvl 5 version rocks all and can take out the first boss in one shot. All you really need to do is get that right away and you have all the money you need to buy all the other upgrades. The game was a challenge until I figured that out. The final boss could have been a little harder too. He was scary looking and all and his attacks were scary but there is that little fine point in between his shots. I never was touched. I think the boss before him offered more resistance.
Oh and not to sound like I'm complaining but the speed boost upgrade doesn't work with the highest engine..
I hope I was helpful with all of this. I'll be looking forward to a sequil.