I'll agree with almost everything you said, and also add that the jump seems incredibly flaky as well, as half the time you want to jump, it just doesn't seem to fire. Almost like the physics and the graphics don't agree when you're on the ground or there's a delay between hitting the ground and when you can jump, or... something. I never figured out the pattern - I just accepted that at least half the time I hit spacebar I was going to return to the checkpoint..