Rather fun and addictive.
I for some reason got a LOT of slowdown at odd times, especially when the vertical beams for that first boss appeared the first time, and right as I died the game just slowed to a speed of like 2 fps or something. I suspected there might be some intentionally bullet-time stuff in the game, but those two occurrences felt odd.
Other than that, this is a solid (if relatively simple) twin-stick shooter with the fanciness dialed up.