5 stars: Refreshing ! Probably one of the few which emulates paper and does not solve itself for you by showing mistakes,or giving silly highlights etc. This makes it the best version for those who want the paper version on screen. Dump all the others, which are pointless.
4 stars: Once I learned how to play, I really got into it. I like this app a lot, the color coding is really helpful. Edit: deducting a star because I can no longer watch videos to get hints - they won't load.
4 stars: I like the ability to enter my own puzzles. The only issue I have with it is that when you select a number, it only highlights the completed cells and the cells where the only pencil mark is that number. It would be more useful if it highlighted all cells with that number, including cells with other pencil marks.
2 stars: Good game that suffers GREATLY from errors in Champions Challenge. I'll frequently beat the time listed only to be told that there was an error signing me in. There seems to be no rhyme nor reason to this; roughly 80% of my times that beat the champion are randomly invalidated due to this error. This has also cost me over 500 coins. Fix it and I'll adjust my rating.
2 stars: I have played this slot because I can't find a better sudoku game but the controls are poor and buggy. The worst thing is you can accidentally overwrite numbers Nd have no function to turn this off. You have an option to spend coins to turn off ads for a short period but this simply does ...