A few days ago I received my m-mount adapter for the GF1 and yesterday I borrowed a Voigtländer Nokton 40mm f1.4 lens to try with the adapter. Due to the crop this lens becomes a 80mm lens but it feels and looks great, thi is how lenses are supposed to look and not like the modern lenses which only have the infinite focus ring around the lens.
I sure hope that manufacturers and here especially Ricoh will abandon the silly focus-by-wire systems and produce lenses with proper manual focus rings and maybe even aperture rings around the lens barrel.
The picture shows a bit the quality you get with this lens at f1.4. One thing to note though is that I have edited the file a bit and added some vignetting.
Also something to be aware of is that the distance markings on the lens don't work with the GF1 and adapter and you can focus over infinity.
Still, it is great fun to be able to use so many lenses on the GF1 and to get a different character from each lens.