Lots of fun, if short lived.
The game had far more than what I was expecting, I just thought it was going to be a simple puzzle game with nothing too deep or challenging in it. Which while most of the puzzles were quite run of the mill and I could see a solution pretty quickly, it still felt challenged. In the later levels you tend to get more devious puzzles and puzzles linked together, so instead of the main objective being "get that box on that button" to complete, you have "get that energy ball there to open a door to get that box to put on a button I saw 4 rooms back".
The game really picks up once you get the double portal upgrade, this is when the puzzles get interesting. In some of the puzzles, the solution is easily figured out but executing can be a little trickier, especially when a button is timed and you only have a short time to do something.
Also what gives this some more replayability is that once you have completed the main story line, you can go back and do some bonus levels that are similar to the ones played before, but with an extra twist.
Definitely worth a play though it is over far too quickly, I wasn't expecting it to be long but it was shorter than I expected.