Just borrowed that camera with 20/1.7 lens from my friend DDB. First impressions:
User interface is very awkward. I had to read the manual in detail just to figure out manual exposure.
AF is very good. Face recognition and tracking work well. Playback controls also awkward.
LCD is good straight on, marginally useful at an angle.
The lens seems quite sharp at all apertures. Image detail and clarity is remarkably good, possibly because of lens-specific optimization. Colors seem muted though. Some sensor noise as expected but with very natural-looking “grain”.
Zoomed-in manual focus is quite effective.
Tightened strap works well for stabilization.
For my use, 20/1.7 isn’t long enough, would have preferred 45/2.8 macro. Not sure if lack of image stabilization in GF1 would matter a lot, but I expect its controls would be better laid out.