Nigel,
I had the Mamiya 7 + 43mm, 65mm and 150mm lenses for a few years. I had an 80mm briefly but preferred the 65mm. A few observations:
1 ) It looks like a kid's "my first camera" so people tend not to be too threatened by it. It occasionally attracts the right sort of interest from those in the know.
2 ) The lenses are stellar in terms of sharpness, lack of distortion and contrast.
3 ) The camera body is mostly plastic. I never had any problems with it but it isn't the sturdiest feeling camera, if I'm honest. I doubt it's rain-proof.
4 ) The meter is very centre-weighted but fine, once you get used to it. It's not like a modern, averaged system like you find on most SLRs.
5 ) It's a rangefinder. You know this already but, as it doesn't have autofocus, you will need to pre-focus or learn to "anticipate", if you intend using it spontaneously on the hoof.
6 ) The lenses are (in relative terms) s l o w. Great results in good light but high ISO or pushed if indoors / low light.
7 ) The longer the lens, the smaller the bright lines appear in the viewfinder - therefore, the more difficult it is to focus longer lenses. I had real issues with the 150mm as a spectacles wearer.
8 ) It's quite large (though not very heavy). You'll need a big bag. Unlike the Mamiya 6, the lens won't collapse / recess into the body.
9 ) If you use a tripod, you'll need to either (a) buy the widget that separates the base plate from the tripod plate or (b) remove from the tripod / plate every time you want to change films (the "curtain" lever (used when changing lenses mid-film) / door opener is on the base plate and is a pain to deal with when the camera is tripod-mounted.
10 ) BIG and bright viewfinder. Great for right eye dominant but not so good for lefties....
Assuming you can live with its idiosyncrasies and slow lenses, you will love the photos you get with it. I've tried to be objective but the best way is to try one. If I was heading back to Mamiya, I'd look at a Mamiya 6 as I like square and it's more compact.
