Canon's entry into the mirrorless market was both late and lackluster. The Canon EOS M was eagerly awaited, but had a disappointing autofocus that was helped some by a firmware update; the EOS M2 only released in Japan and China. But, Canon has made some big steps forward with the EOS M3, available in the U.S. beginning in October 2015. Despite the improvements, there's still some bad points mixed with the good.
The best part about the Canon EOS M3 is that the small body is housing the same sensor and processor as the T6i, so image quality is worthy of DSLR standards. It's equipped with manual modes and RAW for similar flexibility too.
Despite containing the same sensor as the T6i DSLR, the M3 is rather small, weighing less than a pound. The body is built mostly from stainless steel and magnesium alloy, so it doesn't feel cheap in your hands. There's a good amount of physical controls considering the small size. The three-inch touchscreen helps with adjusting the settings as well.
With a solid body and DSLR-like images, where's the bad? The M3 has a rather slow performance for the category. Burst speed is just 4.3 fps. Early reviews also indicate a slow autofocus, though it doesn't appear to slow down much when lighting is more limited. Time between single shots is on the slower side as well. Battery life is more along the lines of a point-and-shoot camera than a DSLR.
While Canon has a pretty good reputation for video, the kit lens included with the M3 doesn't perform the best in footage either.
The M3 has good images and a solid build, though lags a bit behind in performance. The price is just okay considering those features, however, at about $800 with the kit lens. The Fujifilm X-A2 is comparable--while it has a few less megapixels, it also eliminates the optical low pass filter for greater detail. The X-A2 is available in the kit for less than $550. The Sony Alpha a6000 is similarly priced, yet offers an 11 fps burst speed and a better autofocus with similar resolution.
Canon is headed in the right direction from their original mirrorless camera, but there's still a ways to go. If you can find a good deal on the M3, it looks to be a solid (albeit slow) camera, but it's currently hard to recommend when there are similar cameras for a lower price or a better camera for the same price.