Lumix GH1 is another mirco 4/3 camera. Although I still like the flat body design of GF1, for practical reason,the GH1 has a better grip and more direct control on the body.When the GF1 is attached to the external Electronic ViewFinder and the kit lens, the size of GF1 is similar to the GH1.
The GH1 viewer is 5 times sharper and clearer than the GF-1 EVF, this make manual focus with all legacy lens easy and fast,. The moveable LCD screen of the GH1 is great for low angle shot etc.

Recommended old manual lens are lens with aperture control ring on the lens itself. For Lumix M4/3 camera, remember to set the camera(on it's menu) to "shoot w/o lens". Use EVF or the LCD to focus. The metering on the Lumix itself is still useable. Usually,I will set a preferred aperture setting and play with the shutter speed and iso setting to get proper exposure. It's a pleasure to use manual control.