I LOVE it!
This is exactly the kind of very simple to understand yet difficult to strategize aroud experiences I like!
The UI is very easy to read, the visuals are coherent and their simplicity makes them look good together.
The only bad point is that the tutorial is a bit hard to understand, but that's really nitpicking considering what comes after is very easy to grasp by just clicking around and finding out.
Excellent job! =D