Generally, I have never liked rangefinders and find them awkward to use. However, I loved the GS645S in spite of its design. Absolutely one of the sharpest lenses I have ever used. It was a great travel camera, making a number of trips including Germany, Hawaii and Iceland.
Although their form factor and the quality of the lenses has been praised, these cameras received criticism for their fragility. One day, I was working in a very cramped space and had the camera on a short tripod, perhaps three feet tall. While moving around, I knocked it over. The meter died. A few pieces broke off. Everything else seemed to work, but I don’t trust the rangefinder.
This is only my experience: YMMV