Most bikers I see are hunched over on those low-slung handlebars. Most of them say it's to reduce wind resistence. True, but I can't see riding bent over like that.
First, your back is bound to give you grief after awhile. Not exactly good posture.
Second, you have to lift your head up to see, which after awhile will probably result in a pain in the neck.
I like to right upright. Sure there's some wind resistence, but at least I'm riding in a natural style and not like some cro-magnum looking for loose change on the ground.