The game itself is great. 

It was my go-to game for down time for some good weeks. I was on what I believe was the very last puzzle, and been there for a while - One day I turn on my device and by mistake hit "New Game" instead of "Continue" and just like that all my progress was GONE without any confirmation prompt.. 

Other than that it's a great game... :|

EDIT: To be fair I'm on the version 1.2.3, which is not the latest.