Hey, thank you for playing the game and providing such detailed feedback! The very first boss has been a great prototype to test things out, and since then I was able to add different character abilities and difficulty options (which will need to be tested and balanced, of course).
I've been working on some more interesting bullet patterns for this boss as well as future ones after getting the hang of generating the most basic ones. The gameplay loop has been a much higher priority than graphics, but I promise you won't be disappointed in the next update cycle or two =)