It looks like the Chinese manufactures are hard at work making a variety of full frame lens adapters for the Fujifilm GFX system at the moment. Above you can see an older Leica Summilux and Zeiss Otus adapted to the GFX. Sina has images of more adapters and their results here, but if you want to read the translated site you can’t see the images.
Photolari gives an interesting account of the GFX 50S in his first impressions, but the biggest take away is probably in his video (which can be translated via youtube’s player). The GFX 50S has a very long blackout time compared to what many mirrorless shooters are used to. So you will have to adjust your shooting style to account for the blackout time. Also RAW files are 120MB and:
“The lack of agility is – or was until recently – one of the problems of medium format cameras. Other models have already moved tab in this field, and the GFX 50s adds to this evolution. Always thinking in terms of medium format – we are not going to make a football match with it – the autofocus system is fast and accurate.”
Which is a point I have been making for a while. Medium format system are getting faster, but very few people have used a quick medium format system. You can read the full first impressions here.
DSLRMagazine tested the GFX in the French Riviera shortly after the European launch event and while there aren’t a lot of new details they have some new samples here.