There is a really annoying bug:
You can exclude a number at cases where it should not be removed.
Let me explain myself with an example: x-wing011.ss
Here is what I end up into:
3_129_68_
256__4971
98_1__3__
_92___8_3
8_5_2_19_
6__9_825_
5_3__94__
4_95_2738
_28_4_5_9
Well if you don't feel like typing it, just play it. At one point you will have to use the x-wing method on the number 1. Instead of just excluding the number 1 in two cases, you can exclude on the entire line (by selecting the entire line with CTRL and then use the shortcut ALT-1) !! You will end up with no single 1 for that row, which (of course) screws up the rest of the puzzle.
Beside that bug, the program is wonderfull. I really like it, and I hope I will find similar programs for the other 7 "similar" japanese puzzles.