Well, I didn't have enough mana for the end. Took me quite a few tries to get the witch!
I didn't initially realize that the bubbled enemies stay bubbled after you go back to the start. The statues confused me because I thought they were on a timer, but they just send you back to the start if you get too close.
If there was sound, I couldn't hear it -- definitely would have helped with the witch encounter since you'd have some indicator of when she's firing at you from offscreen.
The camera seemed to act a little strange at times -- it sometimes would pan up when I was trying to look down.