The EOS M's images are good, really good. But there's one critical caveat, which we'll get to.
Canon's first mirrorless system camera captures a lot of fine detail, scoring 2200 by 2200 LPH on our resolution chart. Colors are often vivid and quite rich. If rumors are to be believed, the EOS M is a streamlined 650D, with the same APS-C sized image sensor and hybrid auto-focus (AF) inside. It has good ISO performance, able to reach up to high ISO settings with minimal noise and holding on to detail with little smudging.
ISO 1600 is where you get the best balance between minimal detail loss with minimal noise, and at ISO 3200 you start to see a drop in detail. But image noise is still kept admirably low and ISO 6400, while muddy, is still usable to our eyes. Compared with the 650D, the EOS M employs more aggressive noise reduction in JPEGs, while noise is more evident in the 650D's images at higher ISO settings, the 650D's images also retain more detail. The EOS M smooths over more detail to reduce the appearance of noise, but both approaches don't interfere much with overall image quality. Entry-level users who don't have the time or expertise to do their own noise reduction in post-production might favor the EOS M's approach.
One area of concern is that the kit 18-55mm lens exhibits serious barrel distortion at its widest. While it's not uncommon to see distortion at wide angles, it's surprising that the EOS M doesn't offer in-camera correction for it. The only corrections available under the 'Lens aberration correction' menu for the 18-55mm lens is currently only for peripheral illumination and chromatic aberration. The 18-55mm is also soft at the edges when wide open (something we see with NEX kit lenses as well), but at f/5.6 the corners become reasonably sharp.
The critical caveat is this: Even though the EOS M's hybrid auto-focus (AF) system should, in theory, make focusing faster, the opposite turns out to be true. Unlike most of its peers which use contrast-detect AF, the kind commonly found on compact cameras, the EOS M combines contrast-detect AF with phase-detect AF, the kind commonly found on DSLR cameras. We've already seen this kind of hybrid AF on Nikon's 1 series mirrorless system cameras, which have the best auto-focus systems we've seen on mirrorless cameras yet. But, for whatever reason, Canon's implementation falls short.
The EOS M always hesitates a half-beat, racking in and out before locking focus, making it too easy to miss that precious moment. When the camera finally does decide on its subject it is usually right, but it takes far too long to make its decision. When compared against the current generation of mirrorless system cameras on the market, the EOS M's AF speed seriously lags behind. Its sluggishness is bad enough to make this the third strike against the EOS M.
There is one way to make the EOS M focus faster, and that is to shoot in AF Single mode, where the camera will lock onto a single point, instead of AF Tracking or AF Multi. You can use this method to center-focus and re-compose, although we don't recommend that. Another way to make this work is to use the touch-screen to shift your single point on your subject, but you'll have to do this every single time. Since the EOS M is targeted as an entry-level camera for casual users, we can't imagine them using these complicated methods to work around the EOS M's slow AF in the two other modes (and they shouldn't have to in the first place).
Besides the slow AF, the EOS M's AF has another quirk. If you turn Continuous AF on, it will keep hunting for focus, even when your finger is off the shutter release. This is all well and good when you're shooting with the new EF-M mount silent motor lenses, you won't notice it unless you're looking for it. But when you attach a non-silent motor Canon DSLR lens using the EF-EOS mount, this constant hunting engages the focusing motor and produces a whirling sound all the time, making AF-C a noisy affair.