Good except...

Perfectly crafted sudoku.

It only has a display bug on iPhone when you hit the + to start a new game, an ad window appears and messes up the animation preventing the different proposed game patterns to appear completely. When the ad is gone the animation does not resume and the game expects you to select game level or pattern depending when the ad appeared but you dont know what you select.

Aside from that bug its a 5/5

Dalianor about Big Bad Sudoku Book, v3.2