I purchased after hearing MacOSKen podcast, and so far have spent most of my time not guessing at numbers but trying to tame the interface. First, the highlight/shadows make the squares difficult to read, particularly the teensy #s written with pencil. Second, even though Im updated to version 3 of Touch software, its very difficult to select numbers or the X. Sometimes I select number and get a whole row plus a couple other numbers on another row. Lots of times I have to press the X 3-4 times to get rid of it. Many times I have to try over and over to get rid of one. The time Ive spent trying to get the numbers to work predictably is ten times more than figuring out the puzzles. Dont want money back, just want it to work. My iPod otherwise works fine.