Because the sensor lacks an antialiasing filter, the images retain excellent sharpness even as noise rises. JPEGs look very clean up through ISO 800, and they're still quite good at ISO 1600. (Note: test shots at +0.7 EV.)
While ISO 3200 shows quite a bit of detail degradation, it's still quite good in well-lit areas, and many of my ISO 6400 shots were quite usable. (Note: test shots at +0.7 EV.)
