I enjoy bullet hell games, so I certainly had fun progressing through this game, but I really couldn't shake the feeling that there were a few things in the presentation that were "off" so to speak, and since I'm better at dwelling on issues than praise, I'll start with that.
The thing that seems to bother me the most is the hitbox; for some reason, it feels like the hitbox is a little too high since it isn't directly in the center. Perhaps it is the place where it makes the most sense to get hit, but it confuses me! (Especially since I don't like relying on being able to see it)
As I'm sure it's been pointed out already, the difficulty of the bosses in progression doesn't appear to be linear in direction; the first boss was more difficult than several of the bosses that proceeded him, in my opinion, and the difficulty of each attack seems to waver wildly. Using the last boss as an example, a couple of them are challenging, fitting for the final stage; a couple seem to rely on big bullets, and aren't very difficult before too long; the last one can either be a good endurance attack or a contest of how many lives are left when you get there, depending on which direction the influencing bullets take. In other words, the attacks are completely imbalanced! It'd be nice if you could mix things up a bit to make the difficulty a bit more sensible.
Also, you get twelve lives? That seems like both too many lives (in my opinion) and just a plain weird number to pick. (Does that total to the number of lives + bombs you start with in a Touhou game? :P) Not that I'm complaining. (I needed all of them)
Anyways, it was a fun experience regardless of some of its issues. The ship's maneuverability is fine, although a little fast for my liking; the attacks were interesting (even if some surprise you at first); nothing obscures the bullets when they get close to you; all in all, it's a fair game.
(Told you I'm not very good at praising people ;P)