Summary: I agree with the other people who gave this one poor marks. The game does not make good use of the dual screens at all. And sudoku is all this game does. I was spoiled because the first sudoku game I bought for DS was Brain Age - please note that sudoku is only a part of the Brain Age software, sort of a "bonus". Anyway, they designed it so you turn the DS 180 degrees and hold it like a book - the sudoku grid is nice and large, and fills most of one screen.
Summary: This game pales in comparison with the Sudoku found in Brain Age. The only reason to play it on the DS instead of in a cheap paper book are the electronic features. But if the interface is awful, why bother? PROS: The only nice feature this offers over pen and paper Sudoku are 2 minimal improvements: Double clicking on a number will highlight all instances of that number on the grid.
Summary: I started Sudoku on the Brain Age Game. I find the Gridmaster to have a poor and incomplete interface (4 temporaries only) and tiny font. Why it didn't follow the Brain Age system is beyond me. Under no circumstance can I recommend this game. Buy Brain Age and wait for a better Sudoku Game.
Summary: WORST OF ALL, THERE ISN'T EVEN ROOM TO PUT ALL THE "PENCILMARK/HINTS." WHAT ARE THESE PEOPLE THINKING? LAME, LAME, LAME. This game's layout, logistics and overall execution are just plain poor. Not enough room for hints, too hard to see, too small display. I really enjoy the Brain Age version, and assumed that this would be a least somewhat similar.