The GR3 is very customizable, at least compared to the Fujifilm cameras that I’m more familiar with. To me, the best feature is that the GR3 gives three custom settings on the mode dial that are pretty much fully customizable. After some experimentation I think I've settled on a setup that works pretty well for the way I shoot and I use the custom settings all the time. This is how I’ve set them up:
U1 I shoot aperture priority more than anything so this is my default mode. Auto ISO (max 6400), ‘Select AF’ autofocus, default to f/2.8, snap focus at 1.5m, RAW+JPEG. For the JPEGs I experimented with the Positive Film simulation but have now created my own custom color profile with more contrast.
U2 Not how I normally shoot but I have U2 set for hyperfocal shooting at f/8 and present manual focus at 5m. So everything beyond 5m should be 'acceptably sharp' and I don't need to reply in autofocus. I also it set to black & white, just because I'm tending to create more b&w than color at the moment, but I have this mode set to RAW only anyway.
U3 Something of a playful mode, I have U3 set to RAW + JPEG but in square format and high-contrast black and white. So a very different experience to the other modes and it's worth noting that the RAW files it creates are also square.
Most of the buttons and dials I've left to their default settings, such as the macro mode and ISO settings. I have re-assigned the wifi/video button on the left of the camera so that it accesses the crop modes. So press it once and it switches to 35mm. Press again and it's 50mm. Yes there's a drop in resolution and yes I could just crop the files in post. But if I want the image at 35mm then I want to see what I'm getting and judge the distance and composition in camera (rather than get too close for a portrait for example).
I’m still experimenting with the face detection. As with other cameras, I sometimes think it’s good enough to leave enabled and it’s great in some circumstances, then I hit a situation when it doesn’t do what I want or expect. So I still have it switched off more than on at the moment.
I also love the idea of the highlight-weighted metering to preserve highlights. Maybe for landscape shooting particularly this could be a good option. But in practice for the kinds of shooting I do, center-weighted metering gives me better results.
I'm still more familiar with Fujifilm controls and do love having aperture and manual focus on lens, but for a small camera Ricoh have done a great job by making the GR3 so customizable. It just took some experimentation but this seems to work great for what I want at the moment.