That's a bad one. When I was stuck I figured out in temporary mode (not more than 10 steps before a contradiction appeared) whether the bottom right block is set or not. After that I made it almost to the end: but there are three areas without a unique solution: 1) the left eye: 4 options! 2) the right end of the mouth: 2 options 3) the 5 in column 5: 2 options. That's a total of 16 different solutions for the numbers.