It’s challenging but not maddening. You’ll be stopped/stumped from time to time, but patience will pay off. It has a nice rhythm of challenge. If you hit a tough puzzle and beat it, you are rewarded with a bit of a break. Functionality is superb. The visuals are great: and there are a LOT of visual options, including dark/battery-saver mode. With 800 puzzles and more to come, it seems infinite—in the best way possible. I accidentally paid $4 for it, but I am truly so glad I did. Certainly worth even more for the fun and challenge I have had.