Bought the Xbox One version this afternoon and... wow, some of these bosses in the first area alone are downright brutal. I'm not a fan of the Xbox One's controller at all, so that combined with the small space some of the bosses give you to move and dodge in makes this feel extra, extra hard at times.
Nice to see they give you "easy" versions of the bosses just to progress on the map, even if they don't count overall. That should help cut down on some of the frustration of progressing, as clearly getting some more coins to buy stuff would be helpful for me.
The shop descriptions for the items are a complete WTF, though. Add an extra heart to your life bar, but it reduces your shot strength? That's...devilish.