Yeah, Peter Weyland's old man makeup was the one eyesore on an otherwise beautiful looking movie. It immediately reminded me of Johnny Knoxville doing his old man routine in the Jackass movies.
If you were expecting to be shocked and disturbed as you were back in 79 when the original came out, then I can see why people would be disappointed in Prometheus. But, I think in this day and age, its much more difficult to shock an audience like that since they are much more sophisticated then they were back then. I think I went into this movie with the right expectations and ended up really enjoying it.