I know what you mean. I think it's a better "machine" than it's predecessor for sure, but the GRII had greater simplicity and wonderful (especially B&W) tones right out of the box. In my opinion. My last one broke though over-use and I miss it.
For a camera that at first glance feels so familiar, the differences concerning the results are somewhat puzzling - most things are objectively better, but for me, still somewhat hard to predict; highlight recovery is limited (even in RAW), but shadow recovery is a lot better, so protecting the highlights is key, but not always easy if you like your screen uncluttered (as I do). Colours are very nice and respond well to slight adjustments (I never do heavy ones) - most of the time, working from RAW seems unnecessary, but then again, sometimes it seems the only way to get at the full potential of the files. And sometimes, the JPEGs aren't a good basis for editing ... It's kind of irritating to have to swap tools in mid-workflow. But basically, that's just me being too lazy to work from RAW *all* the time.
From JPEG (using Polarr):
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From RAW (using darktable 3.0.0) - apart from the very obvious difference in WB, the RAW just has a lot more to offer, but basic JPEG quality is still high:
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It's like learning a language you feel you should be already familiar with (like listening to Dutch, in my case). It seems to work - until it doesn't.
The GR III is a chameleon - in good light, it just works; this is from JPEG, with just a little work in Polarr:
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Again, shadows look a bit crushed, but colour reproduction and overall IQ are just fine ...
M.