It seems like this is a very good engine for a game that could be very challenging. I admit, I couldn't really envision a complete path through most (any?) levels until I really embarked and thought "meh, let's just see if this works", which is a good sign of how challenging of a puzzler this could be. But like a couple of the previous reviews said, the level designs so far have been straightforward enough that there hasn't been a whole lot of puzzle-solving necessary and I've been able to just run through and eventually find the way out. Future levels could definitely use some branching paths with a lot of dead ends for players who don't know what they're doing.
And since I'm a "musician" after all, it would be nice to use a longer and better loop for the background muzak.