Yikes. Kind of creepy. That site is sort of the foreskin equivalent of that disturbingly obsessive Penis Size Debate site.
Sexually, I don't think there's too huge of a difference for most women beyond aesthetics. Uncircumcised guys might be slightly more sensitive, and intercourse might "scrape" the vagina less due to the several inches of play a foreskin gives you, but I don't think the differences are that dramatic when compared to sexual technique and, well, penis size.
I will say that it seems like only guys who have been circumcized get that super "veiny" look. It doesn't happen to all of them, but all the really veiny ones I've seen (in pictures, so I could be wrong) have been circ'd.