Really liked this one too. Not so difficult - save for a rare few levels that somehow had the pieces arranged in ways that didn't seem to follow the same pattern as the rest of them - but just very rewarding all the way through. Feels like this concept could be done more. Spin-off's with different shapes or level packs, a lot of extra fun to be had with this idea I feel...
One thing that did frustrate a bit unnecessarily I feel is the isometric viewpoint where the pieces float above the board, where you have to focus on their shadows to make sure they fit in correctly. It'd feel much more seamless with less space between board and puzzle pieces IMO. A flat board might not look as cool but it'd be easier to play and control that way.
-cd-