I agree, that it definitely comes down to personal shooting preferences when going fixed focal length.
Personally, i still look back at a trip 7 years ago, when i borrowed my dad's:
28mm fixed, analog, optical wievfinder, and only 160g...one word...FUN!
Since i got my first Digital Camera (a Canon 350D DSLR), i've been waiting and waiting for a digital camera equally fun to use as the Leica Mini, and with high image quality.
I've never really been satisfied with any of my Digita Cameras i've owned that had/has a smaller sensor than APS-C.
If i were to get this camera, i'd definitely get a Viewfinder to mount on top, for me, a good optical viewfinder is the basis for having FUN when shooting.
If 35mm were my prefered focal lenght, i'd be drooling all over the FujiFilm X100S - that built-in viewfinder is great! - But i think it's a little on the heavy side for what it is.
A Ricoh GR with the viewfinder from the X100S would be badass!
But i think i could be happy with the GR ;-)