I'm somewhere between "it's OK" and "I dislike it". If attention is drawn to it, like in the collectibles with the see-through domes, I think it looks very tacky. As something almost subliminal, it's quite effective. I prefer if "in reality" there is no skull beneath the dome, though. I think a lack of eyes, or any point of reference for eyes, makes the alien much more unique than it being another skull-faced monster.
