Pretty straight forward.
The challenge here is not so much figuring out how to fit the shapes into the puzzle as it is getting the bloody physics to behave themselves for 5 seconds. It takes little more than a nudge to send a shape flying across the screen after you've already meticulously nudged it into position meaning another meticulous slog trying to get it back. Can be pretty frustrating, but nothing deal breaking. It's just the puzzles themselves are usually all pretty straight forward.
Not too bad, but..
The concept of the game is not really new, and the game physics feel really wonky. I swear I barely moved my mouse cursor, and the block went 360 at least five times.
I can't help but to notice that the solutions to most of the puzzles were fairly strait-forward, to the point where the felt like a children's jigsaw puzzle: their simplicity is to an extent that a child could figure it out.
Also, if you go back to the menu, or accidentally refresh the page, you should be able to get back to the puzzle you were on before, rather than be forced to start from the first puzzle.