I have the 12x12 and I love it. There are slots every 1/2". Makes cutting strips extremely easy. HOWEVER, I have made a few cutting errors, so that when I cut multiple strips I put a piece of making tape over all the holes I DON'T want to cut in. That way I am sure to get the right size cut instead of one that is 1/2" to skinny.
(The reason the current baby quilt I am making is 4x5 blocks instead of the 5x5 blocks the pattern calls for)