The minimal art and awesome smooth transitions...what more do you need in a game. Loved the design and the animations. It's such a well made game. Could easily see this becoming a mobile game if you add more levels or randomly generate the levels.
The only thing that I didn't like is the eraser button. Just to erase a connection I have to move my mouse all the way across the screen. Right mouse click would be much better in my opinion. Expect that everything else was truly awesome!