I beat the game last night!! That last level is totally insane. You need to take out as many of the wall cannons as possible, while avoiding the moving rocks and enemies without touching any wall in the tight, tight corridors. Basically you have no chance to beat it unless you memorize everything, then it's still tough. Took me hours to finally get it down, luckilly the last board is a blast to play!
I agree with Esteban also, I had parts I knew but would still screw up many times, makes you sooo frustrated. Part of it on this game is there is really no room for error so you can't lose concentration for even a split second.
Anyway, super glad I picked this game up, I had held off for a long time because of it's bad rep. The game is super hard, but the 4th stage is the only one where you feel it's actually unfair, but it's still clearable and gets easier with practice (use the speed burst a lot).
Now to see if I can 1cc the game like SuperDeadite, I don't think I will but if I can beat the 4th stage on my first life I have a chance. I'm still having fun with it so I will be trying.