This game has quite a few bugs that nearly render it unplayable. The levels themselves are difficult and frustrating, but simply trying to access a portal shouldn't be. Falling through solid lines, getting stuck in blocks, unable to get enough height to jump through lines between levels, etc.
Quite a few bugs. I'm constantly losing items that were there before I died. I jumped up to the next level in Seeing Double and I'm stuck. I never made it to above the bar, so I'm stuck in a hole.
Perhaps the game has been updated since these comments complaining about pro mode were posted, but I found pro to be fairly straightforward. If I was off by a small amount, the game adjusted for me. Gandhi wasn't upright, so the game moved him 15 degrees for me. My stars weren't perfect on Bart Simpson, but the game took it anyway. It's not as bad as top commenters make it seem.
The game glitched at the end of the lava level. I couldn't move at all and when enemies attacked, they did no damage. I couldn't do anything, other than restart. It's disheartening knowing I was so close to getting the hard badge. =(