The swapping of the flash for the EVF is the most substantive physical change between the GM5 and its predecessor.
Though Panasonic has made some changes to the design for the GM5, it looks identical from the front. However, it's now made of magnesium alloy.
Panasonic jettisoned the flash of the GM1, moving it to an optional bundled flash that fits in the hot shoe. Instead, the GM5 gets a small but serviceable EVF.
Although it's a hair bigger than the GM1, it's still a pretty small camera.
Since the EVF forces extra space at the top -- the GM1's LCD went all the way up to the top -- Panasonic added some extra programmable controls and changed the back vertical dial to a horizonal one.
Panasonic adds its version of the short-uploadable-movie feature; clips can be 2, 4, 6 or 8 seconds.
It just has micro HDMI and USB connectors.
The camera may be small, but Panasonic makes room for a full-size SD card slot. On the other hand, the small battery still doesn't last nearly long enough.