My first tests are not very encouraging unfortunately.
Not as bad as what was reported by others, but I see clear pixel level artifacts on edges even with totally motionless subjects shot using a super steady RRS 4 series tripod and Arca cube head. This is clearly visible when looking at the image at 100% on a full HD 30 inch screen.
Compared to one of the 16 shots, the resulting image scaled down to 102 mp feels a bit sharper, but the difference isn't as high as it should be.
I don't know if the issue is with the capture algorithm or with the Fuji Pixel Shift Combiner utility, but if what I see is representative of the capability, I don't consider it useful at the moment.
One possible issue is that my test was with the 120mm macro with IS deactivated. One poster commented that using this lens was not recommended due to possible motion of the stabilizing element between shots... maybe... I'll try again with another lens but this in itself would be a problem.
Anyway, I was not expecting this capability when I bought the camera, so I cannot complain, but a bit disappointed still.
Cheers,
Bernard