I'm pretty pro touchscreen to a point. Any driving critical control should be physical. Lights, turn signals, horn, steering wheel controls, etc. Physical controls with physical feedback. Everything the driver should mess with should be either on the wheel or immediately around it and should be physical.

Other than that, I really don't care. When I'm punching in the address on the navigation system, give me a massive screen. When I'm stopped and trying to look up something in my media collection, give me a massive touchscreen. When I'm trying to quickly glance at the map, make it a giant screen so I can see it all quickly. Or better yet a HUD or have it on the instrument cluster.