Though it's not bad, this set of images makes the Olympus PEN E-PM1's JPEGs look a little better than they are. Central areas of detail stand up well at midrange ISO sensitivities (ISO 400 and 800), but the peripheral areas seem to suffer excessive blurring. Still, I think the JPEG compression and noise reduction are a bit better than the Panasonic GF3's, and pretty close to the Sony NEX-C3's.
If you're going to shoot raw, the PM1 ultimately delivers similar photo quality to the GF3 as well as the NEX-C3, and all are pretty decent at mid- to high ISO sensitivities. (Here, the GF3 was shot with a much better lens than the E-PM1, giving it an edge in exposure and sharpness.)
Usually I complain about the hue skew of the default color settings; in the E-PM1, Olympus defaults to a natural setting, which delivers very good color. Its auto, on the other hand, shows some shifts.
Olympus continues to supply the best in-camera special-effects filters I've seen--the filters have a nice set of options and produce the best results. The E-PM1 also has a solid multiple-exposure mode.