First I didnt like the user interface of this app. It looked too crowded, too old-fashioned. But after a while I got used to it, and the look and feel is more then compensated for by the genius functionality. If you are, like I was, transitioning from basic to advanced skill level, then this app is for you. The tutorials That teach you techniques of how to solve more difficult sudokus are just great. This app is addictive. And so much fun because you can see how your ability to solve the puzzles improves. I love this app! Thank you!