The first major complete review with samples of the Olympus OM-D E-M5 is online here:
Robin Wong: Olympus OM-D E-M5 Review: Batu Caves, KL
Also dpreview posted review here:
Olympus OM-D E-M5 Hands-on Preview: Digital Photography Review
And Low Light ISO samples here:
Olympus OM-D E-M5 Low Light ISO samples: dpreview review samples: Galleries: Digital Photography Review