I dont really like the idea of wearing the camelbak, but the alternatives?
On my tandem I cannot reach the waterbottle cage because my husband's back is in the way.
Rather than make him get off the bike everytime I need a drink of water, i wear the camelbak.

on my single, if i am doing a short ride, i carry a water bottle and drink when i get there. If i am on a longer ride, i wear the camelbak because it is easier and safer to drink from it than it is to get the waterbottle out, etc..

Even though i am less than enthusiastic, i really recommend it for safety and ease.