The great thing about iteration is that it has a tendency to repeat itself. The original RX100 might have ended up as a well-regarded one-time offering, but with the 2013 refresh, Sony seems poised to carry the big camera in a small body concept forward into the future.
In Your Hands
From across the room, you would be hard pressed to pick out the RX-100ii from the original RX-100 (with the obvious exception of the added hotshoe), but up close, the added thickness becomes apparent. The RX-100 was (and remains) a truly tiny camera for its sensor size, and feels like it's on the verge of being a matchbox camera. The added thickness that the flip-out LCD display has brought on is not overwhelming, but the new camera does feel more like a middle-weight compact than an overgrown matchbox. However familiarity is good. If the tactile user experience hasn't changed, at least the control interface is consistent between generations as well.
This sameness is both good and bad. The camera is just as portable as ever, but for my personal taste, the awkwardness of the controls on the small body of the RX100 becomes a little bit more irritating on the RX100ii. On the first camera, it was accepted as a price to pay for portability, but I wish they had taken the trouble to redesign the tactile feel of the buttons and control surfaces. Expectations are relative, though. This is still a tiny camera compared to nearly everything else on the market.
Sony claims an increase of 40% in light gathering, which sounds like a lot, but bear in mind that this correlates to just under 1/2 stop's worth of ISO power. For any sensor less than m4/3 size, this is more or less a generation's jump in image quality. Just as a reminder, BSI means that the sensor is constructed with the wiring interconnects below the light gathering substrate (convention is with the wiring above the substrate). Though there are some design implications, BSI generally allows for a clearer path from the microlenses into the photodiode, meaning more light is gathered, and from a greater angle as well. BSI offers the biggest improvements with small, tightly packed sensors where the wiring interconnects take up proportionally more of the sensor's surface area. At 20mp on a 1/1" sized sensor, the RX100ii has photosites at 2.4µm. This is extremely small; by comparison, the photosites in an iPhone are 1.4 µm.
Looking at Imaging Resource's sample images, my estimation is that the 1/2 stop in image noise difference bears out; ISO 800 on the RX100ii is cleaner than the RX100's ISO 800, but nosier than the RX100's ISO 400. Both cameras are usable to ISO 3200, but in truth, a lot of the cleanliness that you see on the out of camera JPEG's is due to noise reduction. For a truly quality result, it's still a camera that I wouldn't take past ISO 800, but because of the relatively slow lens, you'll probably be using ISO 1600 and 3200 more than you are used to. That's fine; the images will still look great: smooth, just not DSLR crisp.
Playing around with my sample unit, I didn't come across any surprises. Though peeping with just the camera LCD display is no way to objectively judge the ultimate performance of a camera, I was able to fiddle with the RX100 and the RX100ii back to back. As I've alluded to, you tend to notice the difference in camera housing more than the difference in image quality. Since none of the other sub-m4/3 compacts on the market come close to the Sony's image quality, the original RX100 would still be the category leader were it not for this refresh. In other words, the original RX100 is still better than the newer Fujifilm X20 or the Panasonic LX7; the RX100ii is just a little bit better.
If there's one great thing about the RX100i, it's that it makes the RX100 look cheap. Sony is asking for an eye-watering $799 CDN for the new camera, while the original now sells for $649 CDN. In my experience, the difference in image quality and flip-out LCD are not worth the price difference. First of all, the articulated LCD is a luxury; though awkward in some situations, you can get by without one if you are willing to shoot stoop/bend/contort or take a few extra safety shots. The improved ISO quality is nice and makes this camera once again top dog among compacts, but getting one over the original RX100 doesn't give you that much more bang for the buck. It goes without saying that there are some decent m4/3 cameras and entry level DSLR's at this price as well, though none are as small and portable.
The price for he RX100ii makes it a difficult sell as a second camera, but if you are moving up from an older compact or a smartphone, it's a reasonable proposition if you never pictured yourself using a DSLR. You would be sacrificing some image quality and system flexibility by forgoing an interchangeable lens camera, but at the level of image quality the RX cameras give, the RX100ii would likely be used for a good number of years. Once again, the 2013 version of the RX100 is a great camera, but just as much a halo product as the first one.