The Olympus OM G.Zuiko lenses are quite compact (like this 50mm f/1.4) and fit pretty well on Olympus OM-D cameras like the E-M5
Bokeh is nice, and the lens can be very sharp when stopped down:
You can also get some interesting effects when shooting into the light, including loss of contrast, and some lens flare, although the lens is still capable of producing sharp results:
This photo is a good example of some of the ideas suggested in this article:
http://www.ephotozine.com/article/become-a-pro-at-using-backlight-in-your-photos-25956