The biggest negative for me with the cgi face is the eyes 100%, spacing aside, with most of the previous practical masks they had cutouts around the eyes and dark makeup blended into the mask which allowed the actors eyes to remain visible, this was something that I feel really added an extra layer of realism and depth to the mask especially with Jungle and City Hunter.
The cgi eyes in this remind me of the Jake Sully character from Avatar or something, can't quite put my finger on what it is but they just don't look very Predator like, the rest of the face is fine though I reckon including the handling of the mandibles.
Like others have said it's really a small issue considering about 95% of the movie features him wearing the mask which looks absolutely fantastic.