You can see processing artifacts as low as ISO 200 (look at the text under the bill) and start to see detail degrading in in-focus areas as low as ISO 400. By ISO 800 you start to see color noise as well. I'd recommend sticking below that to be safe.
Because the default settings push the contrast a bit and blow out highlights, I had trouble getting an exposure that didn't overexpose the text in the foreground.
You can see some of the color noise, but the in-focus areas (top) look okay. The out-of-focus areas (bottom) display more noise and processing artifacts. This is a common problem among small-sensor cameras.
(1/40 sec, f2.8, ISO 800, AWB, spot metering)