Summary: Impressively light for the effective focal length and very sharp up to 200mm. Degrades from 200-300mm. At 300mm you are best shooting at f8 if you can, but you will need a lot of light or a static subject to maintain a reasonable shutter speed. Definitely worth the price - especially since there is really only 1 other super-telephoto lens available (the olympus 75-300 which I've never used, but from what I've read is very comparable to this lens).
Excerpt: For reference, I am a pro photographer/videographer, accustomed to using L-series Canon lenses on Canon DSLRs, and recently jumped into the Micro-four-thirds world and bought two GH-3 bodies and four lenses (Lumix and Voigtlander). I am using my experiences with Canon L-lenses as a basis of comparison, but it's only fair to note that this lens is MUCH cheaper than the Canon equivalent.
Excerpt: I use this lens on an Olympus OMD EM-5. This lens is excellent for still objects and critters or slow moving things. It is great at still but distant critters and at getting detail on close things, such as cactus spines.For these things, it is tack sharp. It is not great at quick focus for such creatures as birds in flight, jumping seals, or for low light work, although you can get lucky on the focus if you have a lot of contrast on which to focus quickly.
Pros: Durable, Easy To Use, Lightweight, Reliable, Very sharp
Cons: Not For Fast Moving Stuff, Not Great In Poor Light
Excerpt: An excellent lense for nature photography. The lense is small and easy to handle. Use of a tripod is recommended, especially during cloudy or badly lit conditions. It's not an ideal lens for fast moving objects.
Excerpt: I've had this lens for a over a month now and love it. It gives me the reach I was lacking to get better wildlife shots. I take it along with the rest of my m4/3 system on a lot of hikes, so the compact light weight nature of the m4/3 system is ideal. I've been pleasantly surprised with the bokeh it delivers at it's max apertures. Low light is what I would expect of a lens with a max aperture of 4.0-5.6. So with low light and action you'll need to use higher ISO's.
Excerpt: Small, light, sharp and hand holdable 600mm. Incredible buy for the price. Initially the zoom ring was a little rough but became smooth with a little use. This is my second copy. The first copy was defective in that it would not focus and the zoom ring was sticky. I would have rated it higher but for the defective first copy. Based on the packaging it was an obvious return.
Pros: Easy To Use, Inexpensive, Lightweight, Sharp
Excerpt: Purchased as an alternative to heavy DSLR camera and lens when hiking. So far I am fairly happy with the photos. The images are a little soft when using the optical zoom to get added distance but not too bad. Tripod needed at 600mm range. Use of remote lessens shake disturbances.