This is a unique and enjoyable little shoot-em up. Whereas most shmups are about precision movement with wildly imprecise shooting of bullets everywhere, this changes it up with it's mechanic wherein you need to gather up enough matter from the map to shoot out. The result is that you have to get skilled at shooting precisely, because if you waste a shot, you have to gather up particles again for the next try. Often if I wasn't sure if I could be precise enough, I would opt to move in really close before taking the shot. It's very fast paced and challenging. At first it was a bit overwhelming with so many particles moving on the screen, but I got over that quickly. They made good art choices which kept the enemies or shots from getting drowned out by the particles, so it was very seldom that anything snuck up on me in the chaos. All around, I was very impressed with the art for this game. Often 2D shmups are made with far less eye candy.
The one bad thing I'll say is that I was rather frustrated by their level progression system. There isn't really a save file that you can continue from. Instead you just permanently unlock levels by beating them, which would be fine except that it doesn't do it by stages, it does it by the larger chapters, of which there are only 4 in the game. This means you have to beat 25% of the game at a time to make any permanent progress. If you call it quits for the night on stage 3-5, then next time you have to start again at 3-1. On the bright side, while you're in a playthrough, you can keep hitting continue when you die, so you don't get sent all the way back for that, just for closing down the game session.
Don't let that flaw stop you from getting it however. It's a great game, but you just need to make sure you have a chunk of time to devote to it if you want to make progress.