Excerpt: Got this for my GH4. I already had the 45-200mm but then I read that there was a similar lens with more pro glass, the Panasonic Lumix G X Vario PZ 45-175mm f/4.0-5.6 Zoom OIS Lens (Black). So, I returned the 45-200 and got the 45-175. So far, I like it.B&H is great on returns btw.
Pros: Consistent Output, Durable, Easily Interchangeable, Fast / accurate auto-focus, Lightweight, Nice Bokeh, Strong Construction
Excerpt: I'm very pleased with this lens. Its a nice extension to the kit 12-32mm kit lens for my Lumix GM-1. Use the GM-1 when I want lighter gear that attracts less attention than my Nikon D-800E (e.g., travel, street photos). So far I've used the 45-175mm for street photos and landscapes. I'm very happy with the crisp quality of the images.
Excerpt: I also have the panasonic 100-300mm, but find I leave this lens on my camera most of the time. The 45mm wide end makes it more useful and the 175mm is still a lot of reach. I find the lens sharp and colorful. The power zoom feature is really nice for video.I love the internal focus. There's less chance of picking up dust and it's just plain a better system. The weight and internal focus make this a very unique lens in the m43 lineup. I really like this lens!