I've been trying compact cameras as a lightweight, inconspicuous walk around backup/alternative to FF/APSC DSLR for travel. Finally a camera with built in EVF, in-body stabilization, and no phony pentaprism wart. I normally use a 5D3 and 7D with 17-40, 24-105, and 70-200 f4. For me, a compact camera must reliably be capable of good 13x19 prints to be worth carrying.
Good: lack of resolution reported by DXO is not an issue with RAW. ran the plastic kit lens, 20 f1.7, and 45-150 thru Imatest - the kit lens is as sharp as my 7D with 17-40 or 24-105, the 20mm f1.7 a bit sharper (much sharper at f4, and sharp wide open). test enlargements to 13x19 show no difference between the 7D and GX7 - also no difference in noise at ISO 3200. Controls are good but took a while with the poor manual to configure. Silent mode is great.
Bad: In-body stabilization with the 20mm only allowed 1/30 - the kit lens IS was fine at 40mm eff and 1/10. I don't expect in-body stabilization to be useful with long Olympus lenses. It needs good lenses to produce good results. With the surprisingly good results from the kit lens (and good Photozone test results) the 45-150 was disappointing. Although decently sharp from 90-150eff, I could not get consistently good test results at 200eff - silent shutter helped - and manual focus got very good results but only on the left half of the image - AF? lens slop? 300 eff is snapshot only. the other tests I could find indicate that this lens is as sharp as any but the 35-100. A better grip and properly placed shutter release would be welcome and I'd be happy to give up the tilting evf and lcd weather sealing.
For trips with landscape and/or long lens requirement I'm still going to take a DSLR, but the GX7 is an alternative to the 7D for walk-around, hiking with little or no reduction in total kit weight as there will be some lens duplication. Otherwise, I can probably be happy with the GX7, but will have to buy a second body, 7-14, 35-100, and probably a 12-35 and another prime - which will save weight at about $1000/lb - hmm!
I do think Panasonic and Olympus offer an alternative to APSC for serious use (too bad Sony doesn't offer NEX zoom lenses to compete).
Can anyone tell me the difference between Auto ISO and Iiso?