The RX1 cost US$2,700! That's a lot of fucking money for something that shoots pictures these days. Compare that with what you pay for the Fuji Xpro-1 and Olympus OM-D EM5, then you'd realize you are paying far too much for that sort of image quality.
Sure, there is a CZ lens, and the resolution from full frame is probably quite spiffy but at that price, I often wonder if you are paying more for the name than the hardware.
Here is a comparison chart for Dynamic Range. Notice that the RX1 under auto mode is rather tight in its range compared to the Nikon D600 and Olympus EP-3. Worst of all is the Nikon D800 which has the exact dynamic range of the EP-3, but let's not go there as we are not comparing what the D800 can do.
I care more for dynamic range than low light performance but even then, the Sony RX-1 fails on both counts. You can go to DPreview.com to do a comparison on your own. I won't bother to do this as the results speak for themselves.
Why Dynamic Range is Important
When you capture a high contrast scene, you want to capture as much details in the highlights and low lights (darker areas) for greater range of illuminated depth. You can't capture something in total darkness of course but if there is some detail to be had in a shadow area, then you'd be better off betting on the EP-3 and D600. Look at the chart above and you will see why the Sony RX-1 fails. The light sensitivity is almost pedestrian! This chart is churned out using the Auto setting, meaning that it will be the most common setting you'd use when you're out shooting.
All digital sensors will perform well in bright daylight. That is why I don't really give much thought to it. In challenging lighting, this is where it matters. You can't have a light range that is too wide within the scene as highlights and shadow areas will be clipped (rendered black or fully white). In the case of the Sony RX1, its main weakness is in the shadows. The puny Olympus EP-3 can capture more details in the shadows while loosing out slightly in the highlights. And what's the cost of the EP-3? Go figure.
If you are out buying a digital camera, then the Sony RX-1 cost just far too much for that kind of performance. But this is not to say it can't take beautiful photo. It can do so as long as there is sufficient light and that is what you should be concerned with.
I often tell people who ask me about what cameras to bring along their trip. I will in turn ask them what they want to do with the pictures and the time of day they will be using their cameras most. If you are just out taking snaps, then bring your iPhone. If you are going to shoot for a stock image company, then use the D600. The Sony RX-1? Only if you are a fashion victim.