Nice balance of story and gameplay. I like how each area has it's own idea.
Also I imagine the core mechanic is quite good at catering to a lot of skill levels since you control how fast you go.
My biggest complaint might be difficulty. The first chapter goes on way too long for an introduction, I honestly thought I'd broke it. Then the difficulty ramps up insanely quickly. I just barely got by on the blizzard climb after trying again and again to the point where I feel like I missed something, and having to start from the very bottom every time grew tedious.
I do like that the blizzard changed as you went though. The story does feel a bit too formulaic and this was a nice exception. And whilst I think it was far too difficult, I do think being tougher than the rest suited the game pacing wise.
Honestly though, I gave up on the boss. A lot of the challenges just had me confused as to what I was doing wrong, like at first I though the guys who come and freeze you you'd have to counter by getting super hot rather than flamethrowering them, and I imagine someone could get hung up there. And the boss seemed like it was going to be the worst, weather of not I get hit just feels more random than anything. I'm sure there is a reliable way to dodge him, but figuring that out would take patience the game has already drained from me.