At first it was overwhelming, but then it got a lot easier.
I'm hoping you did the math, and there won't be unsolvable combinations.
What it boils down to, is making sure your user is not frustrated while playing it, this means you should be able to make him feel like he has a good grasp of the "board". Maybe make the sides different from each other a bit, and make the ability to look at two sides at the same time a little bit easier.
I also had a side flip out when i tried to peek at it.
Otherwise, as a sudoku enthusiat, i'm looking forward to this being finished.