Obviously the G1, as the first camera in an entirely new category, is all 'new' - so here's a few of the important highlights before we get going.
The big news of course is that there's no mirror, so the entire camera can be smaller, and the internal construction is actually considerably less complex.
New 12.1 megapixel (effective) Four Thirds format CMOS sensor with SSWF dust reduction system. Panasonic is claiming improved dynamic range as well as increased resolution. As there is no mirror and the camera works in live view mode full time, the G1 features a newly-designed focal plane shutter that stays open when powered down (conventional shutters are closed when powered down). This makes the G1 rather unusual in exposing its sensor when the lens is removed. Those with clumsy fingers are advised to buy a pair of white cotton gloves.
The new smaller lens mount and reduced flange back distance means that Micro Four Thirds lenses are noticeable smaller than their conventional SLR counterparts - even the already diminutive 14-42mm Olympus kit lens.
High resolution (460,000 pixel) wide viewing angle articulated LCD screen. Interestingly the screen and viewfinder are both 3:2 aspect ratio (the G1 offers 4:3, 3:2 and 16:9 shooting options). Both the screen and viewfinder also offer 60 fps live view. The screen and viewfinder switch automatically using an eye-detect sensor.
Large, bright electronic viewfinder (1.4x magnification, 0.7x FF equiv). The viewfinder uses a field sequential system that mixes red, green and blue images shown sequentially at 60fps, giving an effective viewfinder resolution of 1.4 million dots at 180 fps.
New user interface with SLR-style status panel
Unique features including Intelligent Auto, Subject Tracking and this - shutter speed effect simulation.
Quick Menu, Film mode and extensive photographic controls
Push and turn front control dial
Advanced, fast new contrast-detect autofocus system offering 1-area, 23-area, face detection and AF tracking modes.