Canon's first mirrorless has been getting a lot of flack on the internet. Most of it is coming from the EOS-M feeling a little obsolete out of the box. Although we're sure they'll release a firmware update that can fix some of its downfalls (mostly its lethargic autofocusing) there's really nothing they can do about it's lack of optional electronic viewfinder. Without it, you're stuck with a glorified interchangeable lens point and shoot.
Looks like Canon is already attempting to remedy this. Rumor has it a version including electronic viewfinder will be available by mid 2013. Considering this is their first stab at a mirrorless camera, you can bet the next one will fair a little better. If you're an early adopter sticking to your guns, fear not: There's always the hack community giving some more umph to its DSLR-like innards thanks to Magic Lantern.