sj2: Lots of opinions and lots of people seem to think a camera should be everything to all people. No one camera will ever do that. It is a tool with specific application in mind.
To my mind, unless you are new in the market and have no lens/system, comparison with other brands makes little sense. I have been down the path of owing two systems and did not work.
Lenses are the real investment so to me, makes sense to build a good lens line-up that you enjoy working with. Then fit bodies around your lenses. And that what I like about this little fella.
I can pack it in my bag with the primary Canon dSLR body and lens and when I don't want to lug around the primary body, this little guy comes out and does the job.
Going to sell my m4/3 body and lens now. m4/3 vendors have simply wasted too much time with mediocre lens. If you are new buyer with no existing setup then Sony and Pentax seem like good alternatives except Sony's lack of lens. Nikon with a sub-APSC is a competition?
I was considering m4/3 or other MILC as a secondary system for small backup unobtrusive camera I could take wherever I want without thinking where to put that fat DSLR. But now, as Canon introduced EF-M mount going with "foreign" MILC makes much less sense for me.
Of course I'd have to get some basic EF-M lens but for less frequently used ones adapter will do.
And while lacking viewfinder and stuff this tiny camera will make perfectly good pictures yet be small and unobtrusive. Will do not only as a backup if main camera gets damaged, runs out of battery, etc. but in some situations it'll be simply better (small cameras, especially those looking "unprofesionally" like ones typical compact "idiotencamera" does not scare away subjects ;) ) or even will be the only option (like in places where big camera can't be used without permit due to being "professional"). I would have yet another use of the small one, but it's niche, very niche...
wwcove: Where's the beef?
Mirrrless camera for full frame EF mount wont happen. It makes no sense as it'd be too thick to make a difference against DSLR.
Google "Flange focal distance" - it's a hard fixed parameter of particular mount type - it's a distance between lens mount surface and sensor/film surface. For EF it's 44mm. On (D)SLR it is the space where mirror fits. Then, sensor has nonzero thickness and then there is LCD screen behind it. So ~50mm thicness is a minimum for classic EF camera. You could remove the mirror and still be left with an useless empty space.
EF-M mount has aforementioned distance of 18mm - as there is no mirror - thus cameras can be simply significantly smaller that way.
So don't wait for mirrorless classic EF mount -- it most probably won't happen ever. Adapter is the only real and realistic (and sensible) option.
marike6: In the Nikon 1 review, DPR was heavily critical of the lack of external controls. In this EOS-M Preview, the same lack of external buttons is described more as a feature, not a bug because of the "target audience" caveat. Clearly a GF3 is not as nice to use as a GF1 because of the touch screen, yet it's implied in this EOS-M preview that the touch screen can replace mode dials and ISO buttons. Why is it not OK for the Nikon 1 to remove external controls (Nikon was very clear about the target audience for the Nikon 1) yet perfectly fine for the EOS-M?
I'm more interested if function is easily accessible than if its hard button or place on screen to press. It's simply easier to make them really accessible, bigger etc on that 3" screen real estate not on that 1" margin besides the screen.
Besides... Good touchscreen could be operated in gloved hands easily. Tiny buttons (they have to be tiny on tiny camera if they are tiny on cameras like D800 or EOS-5d) are pretty unusable.
Does that Nikon has a usable, capatitative touch screen? Or even any touchscreen at all?
So there is your answer... Menus driven by some keys/dials combo are simply inconvenient contrary to good quality touchscreens.
nathanleebush: Who is Canon aiming at with this camera? No direct external control and lack of EVF rules out enthusiasts. Soccer moms don't care about sensor size and will balk at the price tag. The Sony RX100 kills this with the point and shoot upgraders, while the EM-5 and NEX-7 crush it from above with EVF, control and IQ (Canon doesn't seem to feel the need to update their APS-C sensor tech). And the EF compatibility is a moot point. No pro is going to be to be throwing their $2k 70-200 on this toy. Touch screen is a nice feature, but there are plenty of places for external dials left blank.
Canon seems to be banking on brand recognition and deep pockets. Will it work? Let's watch.
Sorry, but mirrorless accepting EF lenses without adaptor won't happen. Since it makes no sense whatsoever. EF mount has flange focal distance of 44mm to accommodate full frame mirror. Such a distance makes no sense on mirrorless camera - body would be unnecessarily thick and too big. So your only option will be an a adapter.
One day Canon will certainly introduce enthusiast level MILC, probably with more better EF-M lenses. But I suspect that fully proffessional body won't happen.