From what I've been told by the misses who's in the medical field, there can be a hygiene issue with higher risk of things like yeast infections and UTIs. Also, studies I've seen show a higher risk to STDs.
Got curious to do a little looking and found this:
Sex virus lasts longer in uncircumcised men | Reuters
Personally, I'm snipped. Keeping your junk clean and fresh is enough of a pain already, can't imaging having to deal with that as well.