Originally I was thinking of using tilt, but settled on arrow buttons on the screen.
Since then been thinking that maybe a joystick would work better instead of the button, since from a few people I saw play it on the phone, they seem to think that you need to tap the arrows to move rather than holding the button down.
If it sort of helps, the left and right buttons are on the left of the screen while the up and down are on the right. This way when the game is in landscape mode on mobile, the buttons are not getting in the way of the maze.