I was a staunch Micro Four Thirds advocate, key word being "was". I scoffed at the release of the EOS M, and I refused to get one...well, until prices plummeted a year later.
Well, it's been over a year with the M, and it is the small camera I reach for for all forms of duty. The M gets used so much, I have sold virtually all of my Micro Four Thirds platform gear.
I do not have issue not having an electric viewfinder (EVF), I do not have problems changing settings without dedicated buttons or multiple dials. You adapt to the tool in your hand.
I use the M for street, portraits, environmental portraits, familial events, retirements, astrophotography, macro, everything; and the output is exemplary. I adapt EOS mount lenses with full AF, FD mount, Konica AR, Minolta, etc. I've used 430 ex, Yongnuo and Altura speedlites with great results.
I love this camera, it's output, it's ease of use, it's small yet robust and it will fit in a pocket with the exceptional EF-M 22mm f/2 pancake lens.
It may not have lightning 1D series AF speed, it still is fast enough and accurate.
I like this body so much, I just recently added the European market only M2 to my KIT. T5I sensor, improved AF, shorter black-out time, smaller and lighter.
I have posted many M samples in the EOS M thread, and you can search my Gallery for M samples as well.
Now, I just need to sell of my Mu43 Panasonic G5, no need for that one anymore...I got my Ms!