I couldn't get passed the first checkpoint in the first level. Right after the checkpoint, where you have to land between the eyeballs ... it seems impossible to me. I can live with the controls not changing even though you're upside-down, my problem is that the character has momentum and I can't really figure out how to make him perform precise movements. He always skids too far, or lands to soon, or doesn't pick up enough speed before jumping ... the controls feel very indirect because of that, and so it becomes a matter of chance if the character ends up where I want him to or not ...
I already deleted it ... it's not that I can't enjoy a hard and frustratic game (I love Sqrxz for example, and I am not very good at it) but it must give me the impression that I can somehow beat it by training, and not just by being lucky.
I like the idea though, and it does look gorgeous.