I think the learning curve behind the flame jump is either too steep or the flame jump is just flawed, because the flame jump is not very fun to use
I feel like a restart button would be 'nice', I also feel you should respawn faster after dying(these complaints are kind of the same)
The character sprite looks kind of weird compared to the very sleek art of the levels(might just be me tho)
The really thin blocks feel way too difficult (I think this is connected to the flame jump more so than the block)
I could also say that the game drags a little, more in the beginning than in the end
Really anything else I could say would feel like nitpicking and/or personal taste so, that's all I got. Really though, good job on everything else :)