I think the UI is trying to be a bit too clever for its own good, to the point where it's often difficult to add blocks (the + to add blocks often doesn't appear, and when I have my Chromebook in portrait mode it almost never appears). If the app was actually usable it would have gotten 5 stars. It has a lot of good ideas, let down by a UI that just doesn't work (at least on my Chromebook - maybe it would work better on a phone/"Real Android" tablet).