My first camera and lens (bought as kit). I do not use the OM-30 anymore but the Zuiko 1,8/50mm is one of my favourites:

Unobtrusive design, small and lightweight: Length: 32 mm, weight: 165gr., filter thread 49mm.
The Zuiko is a very well-made lens. The feel of the surface is excellent: The mount is metal with a thick rubber focus ring (only manual focus).
The aperture ring which is almost always attached in front of the lens by Olympus could stop down more softly.
The depth of field button is attached at the lens down on the right. It is by far the best accessible position.
The minimum focus is 45 cm. The smallest aperture is 16. The Bokeh is good till very good (cf. http://www.pbase.com/ltolksdorf/image/64028176 ).
The lens is pretty sharp wide open and very sharp stopped down. Distortion isn't a problem. Fall off is sometimes visible at 1,8 but actually no problem in field conditions.