Maybe its something you have to experience to understand but who looks through a viewfinder like that.
Me... for one.
I wouldn't consider any of the earlier M-series because they lacked any viewfinder. There are just too many situations where an LCD screen is difficult or impossible to use and a viewfinder is so much better. I will now consider the M5 as a compact, unobtrusive, lightweight alternative. It just seems a little expensive initially, but I bet it will drop in price over time.
Hopefully Canon makes a few more prime lenses for the M series.
In the meantime, Rokinon is making a bunch of interesting EF-M primes. Manual focus and aperture control only, but they seem to be getting very favorable reviews and reasonably priced. Currently: 8mm f2.8 (fisheye), 10mm f2.8, 12mm f2.0, 16mm f2.0, 21mm f1.4, 35mm f1.2, 50mm f1.2 and 300mm f6.3 (reflex).
Mikaton is making a 35mm f0.95 "Noctilux".
You also can adapt any Leica M-mount ever made, for use on EOS-M. A lot of different manufacturers have made lenses in M-mount.