Hmm yeah, I think the game suffers incredibly from poor readability (it's hard to read what's going on on the screen) - enemy bullets are hard to tell apart from pickups, the debris and clouds in the levels add to that.
Plus, the boss behaviour includes no telegraphing of any kind, so they are pretty much unpredictable.
This all being said, it's really a fun game and very entertaining. If these weak spots were out of the place, it would be super awesome even!
Hope this feedback helps! :-)