The X-Pro1 has an excellent midrange noise profile and intelligent JPEG processing, which means that under the right circumstances you can shoot as high as ISO 1600 with relatively little loss of image detail and without having to process the raw files.
Shots like this show almost no noise, processing or compression artifacts in the area of focus, and there's just a tiny bit of grain in the out-of-focus areas (plus some chromatic aberration, which is common).
(1/60 sec, f2, ISO 800, spot metering, AWB, 18mm lens)
While you can see some mushiness in the flat areas from the noise and consequent noise-reduction algorithms, there's very little loss of sharpness. This is really good for an ISO 6400 JPEG in a camera less than $2,000 (at least for now).
(1/60 sec, f5.6, ISO 6400, spot metering, AWB, 18mm lens)
In very low light you do start to see more traditional artifacts at higher ISO sensitivities in JPEGs, including hot pixels and loss of detail from noise suppression. That said, I was able to get nearly the same exposure at ISO 250 (albeit at a much slower shutter speed) which was exceptionally clean.
(1/2200 sec, f1.4, ISO 6400, spot metering, AWB, 35mm lens)
That which makes the X-Trans sensor amenable to sharp still photos and which reduces the need for a low-pass filter makes it more susceptible to moiré in video. That, plus you can see some block artifacts from the video compression.
While there's a slight bit of orange in these flowers, it's nowhere near as pronounced as rendered in this photo; the inset, a different shot, more accurately depicts what the flowers look like to the eye. This seems to be a problem with the JPEG algorithm, since the raws look fine (see next slide).
(1/250 sec, f2.8, ISO 200, spot metering, AWB, 35mm lens)
This shows the huge difference in accuracy and quality of shooting JPEG vs. raw with the new Fujifilm sensor. The bottom raw is corrected to allow for the greater dynamic range necessary to accurately render the extreme reds and recover detail in this shot (the inset is the JPEG).
(1/280 sec, f5.6, ISO 200, multi metering, AWB, 18mm lens)