User interface: great.
Relayability: none. Scoring for the "pathmaker" is just plain worthless. Your score is the number of mines, so after going for the large map you start with pathetic difficulty, then medium, that's a bit of a challenge. Then hard.
OK, the deal with minesweeper is that you need to reduce the number of times you have to guess to a minimum, because each time you guess you have between 20 and 50% chance of dying. If you have to guess more than 3 or 4 times you might as well play russian roulette.
At "hard" difficulty on the large map there's basically zero chance of reasoning your way through the map without having to guess at least a dozen times. So instead of being a test of skill, it's a game of chance... is there a path that it's possible to reason through or not?
Needs to have "hard" changed to "impossible", and two more levels. Oh, and something done about adjusting the scoring by number of guesses or something, so there's a way to improve your score by improving your skill.