10 out of 10 points and recommendedSolid, fast, weather resistant, very high optical quality. Tripod collar Excellent micro contrast and detail rendition.A little heavy for the m4/3 system but not too much so. Keep in mind it is equivalent to an 80-300 F2.8 full frame angle of view.
I haven't used this lens a lot yet but what I have shot with it has been of exceptional quality. Fast, reliable, well built, weather resistant, top level optical quality, excellent micro-contrast and detail rendition. Love the focus clutch so that can use it in full autofocus or pull back on the focus collar for smooth manual focus. Used with my OM-D E-M5 Mark II, I usually use it in auto mode with manual fine tuning. Olympus PRO lenses are all top quality and can compete with the best that anyone else produces. Oh, and let me not forget the excellent close focus at all focal lengths. (20" from the front of the lens). It is internal focus and internal zoom. The autofocus is lightning quick using two separate focus motors to adjust different lens groups and maintain the IQ regardless of the focal length or distance. The best lens I have ever owned in almost 50 years of photography.reviewed May 4th, 2015 (purchased for $1,499)
10 out of 10 points and recommendedFast, well built, close focusing, weather resistant, sharp.EDIT: Thought of one. The auto manual clutched focus ring can be a little loose. Easy to bump it from auto focus to mechanical manual focus. Minor issue but I've done it a few times. Would be nice if it was a little stiffer to pull back.
This is the second best lens I have owned in almost 50 years of photography. The best is its companion 40-150 F2.8 Pro lens. A little larger and heavier then some m4/3 lenses but not so much as to be a problem for me. Optical quality is great at all focal lengths from F2.8 through F8.0. minimal distortion. Excellent micro-contrast and detail rendition. Close focus so good it is almost macro, at all focal lengths. This is my most used lens and never lets me down. (Waiting on the new 7-14 ultrawide pro zoom though). Prime lens quality in a zoom lens. Can't say enough about it when used with my OM-D E-M5 Mark II. NOTE: Price was price when bought with a camera body. ($200 discount)reviewed May 4th, 2015 (purchased for $799)