I have tried many sudoku apps, including one that was featured in an App Store writeup. This one has the best user experience of all. No fancy animations that slow down your interaction. Separate number pad for notes vs actual values (this saves a lot of interaction time). The ads are placed above the number pads so that it is easier to reach them with your thumb. Works well in landscape orientation as well. The pencil button fills a square with all values as notes (a feature I wanted for a long time but could not find until this app). Click the pencil button again and it shows notes of only the numbers that are not already in the block or row or column (this is really convenient but I prefer not to use this to give my brain more work). Click the pencil button once more and it removes all notes. This too is great interaction design (A single button rather than multiple buttons or settings).Visually very clean and pleasing as well. Notes are clearly visible (not covered by a border like in the app that was in Apple’s writeup).

This game is peaceful and relaxing to use and that is it’s main purpose after all. Other sudoku games have unnecessary complications and distracting graphics. Having to change modes in order to note or place ruins the flow. How can you relax and concentrate with unnerving flashing and every time you place a number? The worst one actually rotates and blinks all the numbers and sends congratulatory messages every time you complete a row. Jeez, give it a rest. This game is the best because every aspect is simple, all on one screen, everything you need and nothing you don’t. Now, if I could just do away with those annoying ads...

I like the simplicity of this app. You have notes and answers on the same page so there’s no need to flip the numbers to be a different option. It’s about as close to playing in a weekly paper publication as you can get on an app. The only thing I don’t like is that the option to use a number doesn't disappear whence you use them up. But I get it. It adds a degree of challenge that doesn’t deter me. The degree of challenge in levels is good. Hard is a solid game but quickly doable for my skill level and the expert levels are quite difficult.

This is my favorite sudoku app, and there are a lot to choose from. I have the paid version. I love the interface. It’s clean and uncluttered. I don’t pay for many apps, but I bought this one because I think it’s an excellent product. I only have one suggestion. I would love it if you had an option in settings for keyboard clicks. Sometimes if I’m playing fast, it would be nice to hear feedback to make sure I tapped on a number. But seriously, this is my go to sudoku. I rarely use magazines for puzzles now.