Summary: I bought this lens to be able to use it on my two cameras LUMIX G-2 and G-3, micro. As I already have a lens Lumix G Vario 14-140, needed a 45-200mm, for complete versatility. I consider this lens as good quality, at an affordable price. I have no criticisms to make regarding this lens.
Summary: Bought this zoom lens on eBay for my Panasonic DMC-GF3 camera and took it to the race track. Detail is amazing, and the 200mm zoom (equivalent to 400mm with 35mm cameras) allowed for close-up shots of the cars in the pit stops from the top of the stands. Video performance was also very good. Autofocus could be slightly faster for high speed action like races, though.
Summary: I bought a Panasonic GF-2 and got the extremely popular 20mm lens. Of course, it had no zooming capability. So this is the only zoom lens I own. It was reasonably priced, and zooms quite a great distance. The lens is hard to hold, but that's to be expected with the micro 4/3 system. My only real complaint with it is that the photos it takes are not as crisp and amazing as with the other lenses I have.
Summary: So I had this lens before selling it to get the 45-175 X lens. The 45-200 is a very nice but somewhat heavy lens (for a Micro-4/3'rds camera). The barrel also extends when you increase the focal length (unlike the X lens). So if you're using one of the smaller m43 cameras, you have this heavy, long lens on the front which makes the camera very front heavy and a little awkward. Optically, it performed fine though and it is cheaper than the 45-175 X.
Summary: I've had this lens for a little over three weeks now; and i have to say i have really enjoyed it. I have this little guy paired with my Olympus PEN-EPL1, and no problems thus far. Of course, don't expect spectacular results at 200mm. I find it to be a little soft like most others. But, with time and patients, you will be able to find the sweet spot. this lens shines in certain areas.
Summary: I purchased this lens and so far is a very good performer. Please be advised to update the lens as soon as you get it. The lens is not very sharp after 160-170mm, but for the price you can't get anything better in the m4/3 world. REMEMBER TO UPDATE THE LENS FIRMWARE!!!!