I've had this lens for 3 months, of which 3 weeks were in Indonesia, where it was thoroughly tested. I use it primarily for bird photography, for which this lens is unbeatable; the 300 - 1000mm reach at f4.5 - 5.6 is unparalleled across all systems! The size of the lens (thanks to the MFT sensor) is remarkably small, and the weight is manageable. I'm able to use the BlackRapid strap and hang the camera/lens without constantly bumping into things. I use it with the OM-1 II body; the combination produces very high IQ across the zoom range, with some drop-off with the 1.25x activated. It's clearly sturdy, and stood up to the heat, humidity, rain and mud during the recent trip. So, no regrets in plonking a portion of the nest egg!! I dinged it one star (1/2 star if possible) for some of the irritating (to me) aspects of the lens. The hood is monstrous and the hood cover is even more ridiculous (they have been safely stored in the box); it offers no protection against fine dust. I replaced it with a very sturdy and shorter Zemlin hood and got a Zemlin lens cap (very happy with these). The tripod collar has a clever (spring-loaded?) 90 deg stop, BUT this makes trying to rotate precisely to a different angle not the easiest. The knob to tighten the collar has to tightened really hard; otherwise it tends to loosen. The zoom ring, in my opinion, is too easy to turn. When carrying it on a strap on the hip, the zoom ring rotates. In summary, if you need the long reach lens, and have the means, I can't think of anything else that OM offers that even comes close!

This lens is absolutely amazing! My only regret is not purchasing it sooner. The reach, image quality, and focus speed are outstanding. It hardly ever leaves my camera now. There’s no noticeable drop in sharpness across the focal range—it's tack-sharp from 150mm to 400mm. The constant f/4.5 aperture is a real advantage, especially in changing light conditions. And if you need a little extra reach, the built-in 1.2x extender at your fingertips is an awesome feature.

This is an expensive lens, there's no doubt about it. But if you have the means to buy it, you won't regret it. It's extremely sharp, fast to focus, remarkably lightweight for its size and capability, and the handling is superb.

I regularly use this lens for sports photography and bird photography. Its so light weight and tack sharp. I love love love this lens!

Wanted this lens for quite some time and do not regret getting it. Weight to flexibility is great as I am not muscular. I have no problem carrying it around. Being a f/4.5 all the way through will allow me to use a lower ISO in dark locations. This lens will allow me to make better nature images and allow new ones.