Large Four Thirds (17.3 x 13 mm) sensor Large sensors provide shallower depth of field and a nice blurry background for your portrait shots.
Average Resolution Sensor: 16.0MP Panasonic GM1's 16.0MP resolution is not the best in its class but you can still manage relatively large prints of your portrait shots and crop without losing too much detail.
Average Ergonomics&Handling Good handling and existence of well placed physical controls on the camera body is very important during portrait shooting. It is faster and more intuitive to change the camera settings with dedicated buttons and knobs instead delving into the menus on the LCD.
No Image Stabilization Due to the lack of sensor based Image stabilization, Panasonic GM1 users have to rely on lenses with optical IS in order to maximize the sharpness of their handheld portrait shots. Currently there are native Micro Four Thirds mount lenses with Image Stabilization for Panasonic GM1.
No Built-in Viewfinder In the lack of a a viewfinder, holding the camera away from the body while using live view is not very stable, especial with heavy camera bodies and lenses. Besides, LCD screens are very hard to read under bright sunlight.