The boss has some high HP, and too many invulnerability frames. His attacks aren't particularly fast, but the amount of bullets he summons is far too high, so you must be very patient with him, but not too patient, otherwise you'll get RNG-pwned in a few seconds. The second and the last attack are particularly annoying with this. The first attack isn't too hard, once you get used to it, but can get some people to rage quit instantly. Same for the third attack. I would find it to be a fun fight, if the second attack didn't exist, but so be it. I wouldn't recommend it to many people, but if you're looking for a hard boss that's not an avoidance, give it a try.