Also got to wave 8. This game is very fun, and I like how the camera moves, but I think it doesn't go well with the screen shake (I think that's what made me a little dizzy). I think the powerups should be more frequent because they rock, using different weapons is great, and kiting enemies to blow them all up with the rocket launcher was awesome.
I think there could be a indicator to show where enemies are because in the beginning I spent some time looking for a lost enemy that was wandering around the map. I also think the hit feedback could be improved: I dig the effects, but maybe the enemies could flash or something when getting hit? But using other weapons as the machinegun or the rocket launcher does improve that.
Other than that, I like the minimalist style, and the game is easy to pickup and play. I think you've done a great job here!