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It can be bad in certain circumstances, and it will flare somewhat easily. A lot depends on the angle and focal length. Sometimes it's bad, other times it's fine. I did not notice a difference based solely on the body as to how it performed in that regard. It's really the lens' one major weakness. (the only other real negative is that it's not as good in the corners at infinity as it is closer up).
For instance, this image shows it pretty much at its worst (this is on the GX1):
Here it's not too bad (this is on the OM-D). You can still see some flares in the concrete on the right half of the image, but it's not really distracting like it is in the first example.