I've done it quite a lot and its a very intimate and very erotic feeling. A girl offering WS should know to obviously drink plenty of water before you arrive. Then its up to you how you want to play it. I've had girls stand over me in the bath and release all over me, or pin you to the floor then sit on your face and pee, or be on all fours over my chest kissing me while letting themselves pee over my cock. Yeah, i've let one or two pee in my mouth, though it gets spat back out, usually back over their pussy, which seems to turn them on more. Taste wise, depends how much water they have drunk, but a bitter taste I would say.
Had a few girls who then asked for me to piss over them, which, can be difficult if you have a beautiful girl under you looking up at you and your trying not to get a stiffy!
Pee is sterile by the way.