I liked the game and enjoyed the puzzles in general, but I was not a fan of the cage system. In a few of the levels, I found it really difficult to maintain the unlocked state of the cage long enough to do anything before the lock would pop down just enough to lock again, resetting any of the objects I moved back into some horrible position. This was especially true for level 40, where I spent two hours because the stream refused to be steady enough for long enough to keep the cage unlocked long enough for me to finish the level. I have no idea how the walkthrough managed to make it look so simple.
I did find a bug in that objects in the top left corner had a tendency to stop responding to clicks, as if they were disabled because they were partially covered by the Menu button or by an invisible achievement dialog. A good example would be the gravity switch in level 51. I couldn't activate it unless I clicked very low on the object. If I pressed tab I could find the "X" for the close dialog button of an achievement, which would show up when I pressed it, so I'm guessing that's related.