Challenging? That's understatement.
This game will mop the floor with you.
It has incredibly annoying sections where you have to run from lava and you have to pretty much memorize maze and run through it with perfect timing... And that would be easy after dying for about thousand times XD

It's not a bad thing though. That game is simply created for specific group of people. So if you like to smash your genitals with a hammer and then pour vinegar all over it... Do yourself a favor and buy this game!

PS. I finished whole game and replayed some sections later - and I didn't find any bugs.