Regularly crashes when going to a new game, forcing you to view an ad when you restart the app. Good for maximizing ad views. Not good for users.
An already bad user interface turned awful with the addition of popup ads in the middle of a game. If you are racing against the clock, forget it. (Havent seen this happen lately)
Press and hold to place a flag is too slow to use on a regular basis. Flag mode helps that; but it is awkward to switch between modes, and you cant clear a single square while in flag mode. If you accidentally place a flag, erasing it is a pain, as you have to click twice to pass through the useless question mark. As you pan across the board, it would be nice to have a clear indication that youve reached the edge, such as a bright border.
And then there are no statistics such as top scores or averages. No comparisons with other players.
Even the help section has a bad user interface. Standard gestures dont work to flip pages. There is no way to go back one page. And what the help shows for a cleared square that is empty (white) is not what you actually see in a game (blue).