Imaging Resource posted the full review of the compact 35-100mm Panasonic zoom:
Optically, the Panasonic 35-100mm Mega O.I.S. Lumix G X Vario is very good for the price – there are some very slight issues with corner softness and de-centering with our review copy, but nothing to write home about. For what it does, the lens does it very well: the only performance item I might have a problem with is that the variable aperture reduces quite quickly. For example wide open at 35mm the maximum aperture is ƒ/3.5; zooming in to 50mm, your maximum aperture is ƒ/4.9. This will restrict your shooting style a bit; you’ll either be shooting outside, with a flash, or you’ll need to boost your ISO settings.
Panasonic has had a 35-100mm ƒ/2.8 zoom available for some time now, but the casual Micro Four-Thirds shooter could have been put off by its $1,500+ price tag. Panasonic has wisely provided a less expensive option that will match extremely well with the Panasonic 12-32mm ƒ/3.5-5.6.