Short n sweet. I do remember this from that 12 games in 12 months challenge, and I also remember it controlling somewhere between ass and biscuits, constantly fighting against the slippery movement and unreliable turning speed.
This is a lot more fun, and the more Ikaruga-type switching is a lot snappier, but I do feel that some of the player finesse is lost in the process. Never ended up dancing with enemies so much as I was mercilessly gunning them down. Much faster/more aggressive enemies with a bigger emphasis on ranged attacks would at least encourage player movement would really up the ante.
You've got a solid shooter on your hands, slightly inspired as it is, and I like the theme. Nothing like some good old fashioned demon hunting.