Without the ability to view the raw files, it's hard to make a judgment about the camera's best noise level, and the E-P3 complicates it by defaulting to what I think is an overly aggressive setting in the JPEGs. The midrange ISO sensitivities here look a little better than in shots taken in the field (see subsequent slides), but I generally wouldn't shoot JPEG beyond ISO 200 with this camera in standard noise reduction, and guesstimate not beyond ISO 800 for raw. On these shots, you can see the detail start to degrade between ISO 400 and 800, and spot the color noise at ISO 1,600.
Here you can see how aggressive the noise suppression is at the camera's default (standard) setting. The low setting displays more grain, but it retains far more detail. I suspect that shooting raw and processing with better noise-reduction software will gain you at least a stop of latitude of grain.
(1/30 sec, f2.0, center-weighted metering, AWB, ISO 800, 12mm lens)
A combination of its tendency to underexpose and a flash without a lot of throw (despite a guide number typical for its class) results in very nicely exposed close-up flash shots. Olympus includes a couple of useful flash options: you can opt to keep a warm white balance when shooting with flash in auto WB, and you can set it specifically to change to flash WB when using flash.
(1/60 sec, f3.5, center-weighted metering, AWB, ISO 200, 14-42mm II lens at 14mm)
Like the noise reduction, the default sharpening seems a bit aggressive to me; this is sharper than I'd like unless I were going straight to print. It's a very consumer look that doesn't belong in a camera of this class.
(1/160 sec, f7.1, +0.3 exposure, spot metering, AWB, ISO 200, standard NR, 14-42mm lens at 30mm)