MarcMedios: No viewfinder, no interchangeable lenses, no sell.
Having no viewfinder not only makes it more difficult to frame and compose the shot, it basically puts you at soccer mom level. The add-on viewfinder then gets you back to SLR size and conspicuousness
Interchangeable lenses are the hallmark of a professional camera, the Leica M3 already had them and it was in what year, 1492? 1860?
Having a full frame sensor is not enough if the camera limits your creative freedom in an arbitrary way. Why have only a 35? Why not a 28? or a 37? or a 49?
As a professional, I love my RX100, I can sneak it into places, fits in my pocket so it is always available, gives me a large sized jpeg, can shoot raw, and for $650 it is really a good deal. The 4:1 zoom is basically similar to my go to leans 24-105 f4. But it is a point and shoot and makes no pretensions of being anything else.
Photographers who buy the RX1 are not thinking with their heads, it is ultimately a very limited camera.
Even with the optional viewfinder the camera is much smaller and less conspicuous than any dslr.
There have been and will be many cameras with fixed focal length lenses. I don't think interchangeable lenses are necessarily the hall mark of a professional camera and many applications don't need them.
The 35mm lens was considered the standard lens for photojournalism and is easy to frame without a viewfinder. Therefore a good choice for a fixed lens camera.
For documentary work this looks like a very interesting camera.