Summary: I've had this lens for about two months. I have found the image quality to be excellent -- but, it must be used with a tripod to obtain that quality. Although it is a fairly slow lens in terms of aperture speed, I find that the range relative to effective focal length is about what I need anyway to obtain proper Depth of Field. It is very well made and feels solid. It focuses fast and very accurately.
Summary: I've had this lens for a month or maybe a little longer. My first impression was 'Wow what a light and tiny long zoom lens!' I think so far that size and weight are the biggest pros. I bought it to replace the Zuiko 70-300 which is larger, heavier, half the price and needs an adapter to mount it to m4/3 cameras. Pros: ---Light and small for such a long zoom. Very easy to take along when you might leave a larger/heavier long lens at home. ---Good contrast.