Photography Blog reviewed the Canon EOS M3. In the conclusion:
[…] the EOS M3 is […] a good camera, and if you already have a number of EOS lenses, it’s a logical choice if you want to reduced the size of the overall system. With the addition of a much faster AF system, control and exposure compensation dials, bigger handgrip and a tilting LCD screen, more experienced photographers will find much to like. It really does need an integrated viewfinder, though – the days of buying an expensive EVF that takes up the flash hotshoe are long gone when all of the EOS M3’s principal rivals have one built-in, in a similar body size and at the same price-point. In terms of image quality, the EOS M3 happily fits the bill, with the new 24.2 megapixel sensor delivering very pleasing images throughout the ISO range.