I currently have a black 3G, I didn't really like the white when it came out because of the front being black still but as I have seen it more and more I have warmed to it, so much so that I think my next iPhone will be a white one (that is if the next revision still has the option of course).
Mind you, call me old school but I still love my white iMac and 20GB iPod colour, the aluminium looks good, but I think white is a distinct trait of Apple (or at least was until the shift to aluminium/other colours).
All in all, I don't mind either, but seeing as I own a black one, given the choice, next time I would go white I think