>>3299549I also have a GS645S (apparently quite popular here)
Build quality isn't exactly premium. Lots of plastic, and if you read around a lot of people say the weird bar that sits around the lens is a little fragile if you bump it too much. I have taken that to heart and baby mine quite a bit, but I've been shooting it a lot for a few months now and it hasn't shown any issues. The obvious benefit of the cheapened design is it is super light, less than my FM2 with a lens on it.
Couldn't be happier so far.