Your character can disappear at the bottom of the screen because that's the punishment if you get caught in one of the obstacles. Usually it supposes an insta-death, but it is a valid decision because if you have enough skill you can just recover the lost space using the roll. And yes, you lose a lot of points if you get hit, but you can perfectly get 24.000 points with three misses or so. You
don't have to do a perfect playthrough to beat it, which is fine.
The controls are stiff... well, because it is a quite simple minigame and you only need to move between paths, jump, and roll to recover and get through enemies. In Bee Bop the bee controls just bad and the jump physics and flying animations as well as the collisions with enemies, platforms and the fire, are half-baked. The difference is that Bee Bop is easy and Hurdle Hijinx is hard, so people get mad at the second one when actually is a better designed and more polished minigame.
You can complain that it is long and hard, but let's not use the terms "bad game design" and "unpolished" to everything.