I just carefully read the preview at dpreview.com, and looked at product images several places, and I can certainly say that my interest in trying an RX1 is increasing. My Canon 5D has taught me to appreciate full frame, and f/2 is certainly fast enough for much of my shooting; I tend to stop my 1.2, 1.4, and 1.8 lenses down to 2.0 to 2.8 in low light, unless I absolutely need a wider aperture. While there is only one possible focal length, it is a very useful focal length.
The RX1, or a potential derivative model, might finally extinguish my desire to eventually acquire a Leica digital rangefinder, though this is largely dependent upon what Leica and other manufacturers might announce in the next couple of years.
I certainly do not consider a Sony to be a poseur's camera, at least not in my circle of photographer acquaintances, where Sony tends to be the butt of jokes.
The cost, compared to a 5D Mark III, which I mentioned earlier, does not seem quite so excessive, upon further reflection, considering the sensor and the lens. A Zeiss 35mm 2.0 lens, in Canon mount,
plus a 5D Mark II or III, would be quite a sum of money.
The negatives, from my point of view, are:
(1) One must choose between the accessory thumb rest, or the external EVF. This is a quite small camera body, and may be too small to balance the lens. Of course, there are generic external grip options that can thread into the tripod mounting hole, and in the future, there may well be grip or thumb rest options tailored to the RX1. I consider the EVF to be very important.
(2) When I spend this much money, to get a full-frame digital camera, I would like a second memory card slot, as with the current Nikon and Canon full-frame DSLRs. That may be, however, asking too much from such a tiny body, and in reality, I have yet to lose images due to a corrupted card.
(3) I prefer mechanical control of aperture and focus. The RX1 lens appears to be fly-by-wire. This is not, however, a deal-breaker, just a preference.
Moreover, the 5D3 seems to perform very well in low light, which is a major priority for me. (See the image of the cat that Jiko posted in the official 5D3 thread!) The RX1 is competing with it for available funds, and its low-light abilities are as yet unknown.
Canon 5Ds R/7D2/7D/5D/40D/1D2N; Nikon F6/D3s/D700/FM3A/Coolpix A. Lens selection undergoing changes; some favorites: Zeiss 2/135 APO Sonnar, Canon 100mm f/2.8L Macro IS and 135L, Nikkor 14-24/2.8G and 200/2 VR.