I actually liked the first boss, although I usually don't like the gimmick it uses. I won't even comment on the second one, and the third one had one particular attack which could RNG-wall you, but it was just one, everything else was fair. Aside from its HP, of course.
The stages are...Interesting at first glance, but the traps get repetitive quickly (Some are well-made, but after a while you can easily guess what's going to happen next for the most part). There's one medley stage with no traps (And as a fellow medley stage, it had to have the famous GB screen).
Visuals are nice, but the musics aren't anything special, and they restart. My experience with this game was quite a bit more meh than I expected. The only fun stages were the third one (World's Hardest Game music, nice visuals and overall well-designed) and the seventh one (Last stage, features all the gimmicks from the previous ones used in different ways, most saves have the right amount of traps, and there are more unpredictable traps than the usual. Fourth one was too much of a breeze to be enjoyed, and the other ones got repetitive too quickly, just more of the same with different visuals.
Not sure if I would recommend.