I rode mine in the rain for the first time the other day.
If you're used to getting drenched on a normal motorbike, the Downtown is amazing - just make sure your knees and feet are tucked in behind the plastic. As long as your moving, you stay pretty dry. When you come to a stop you get wet, but that's to be expected.
Mine has a Givi screen fitted and whilst I find it quite noisy (I'm 5'10), earplugs on linger journeys tend to sort that out. In the rain though, the screen is the perfect height for clearing my visor.