Out-friggin'-RAGEOUS!
You could put this in an arcade right now, and I'd put a quarter in it pretty much once a week. This ranks right up there with Gyruss and Time Pilot as games I'd play in a heartbeat given the trifecta of time to waste, boredom, and loose change.
The bosses are fantastic, and the combination of weird enemy motions, full screen coverage of both your weapons and of enemies, innovative shields, wild animations, actual tactics against sub-bosses, and coherent style make this a game that, transported back to 1982, would have been mentioned twenty years later as one of the all-time greats. That's quite the accomplishment.
From a thirty-five year old Old School gamer who was around to play all the greats firsthand...
Bravo.