I like the artstyle of this game a lot. Difficult jumps are okay, but only when the system isn't broken. Keeping in mind this is a 0.1 version, I'm sure things will be a lot better in the future, though. Stuff like platform collision, ghosted jumps and "Press E to restart" sending you to the main screen are things that will get fixed, I'm sure.
From a game design perspective, though, NO ONE wants to go through a boring and heavily punishing platforming section between every boss attempt. Seriously.
Also, you cannot dodge the boss's attack where she goes from one end of the arena to the other, but are forced to use the parry attack. This is okay, if the game even told you about it and taught you how to use it in a less-risk environment (and if the attack was reactable, but the parry has too much startup before it's active to be able to). Basics of game design, really.
Again, I know this is just a 0.1, but it's better to establish good habits beforehand.