Coming back after a week to share what I thought of it:

• I loved the app itself and all the different ways to input values
• the different game modes are quite creative
• all the extra restrictions added by the different game modes make the puzzles a bit too easy for my taste
• miracle mode is fun until you get a few numbers in, but then it becomes quite straight forward again.
• all of the puzzles (at least as far as I played) follow the same pattern and when you notice it you can skip the whole sudoku part and answer it just by pattern recognition.