I own that it actually fits me fine, only problem I had was with the nose piece area, and that was just because it was sculpted to fir the actors face not mine.
Yeah, his head is extremely small. They actually upsized the prop by about 10%, and it's still too small for most people. I've tried to do some work on it to make it better, but I think it'll just sit there until I can do my own version of Cyclops.