You asked
Is the olympus om d e m10 good in low light?
The site doesn't rate the E-M10's high-ISO performance directly. Its Micro Four Thirds sensor is smaller than APS-C or full frame, and the sensor guide puts full frame at about two stops ahead of Micro Four Thirds in low light. So it's not the camera to pick for dim venues if that's your main job.
You can still shoot in low light with a fast prime, which gathers far more light than a kit zoom. From the E-M10's lens list, I'd look at the Olympus M.Zuiko 25mm f/1.8, the Panasonic Leica DG 25mm f/1.4 II, and the Olympus M.Zuiko 45mm f/1.8 for portraits. Primes versus zooms explains why they're worth the swap. The E-M10 page has the full lens list.
Written by Claude from this site's pages.