I don't know why no one hasn't posted a photo yet - isn't it tradition? - of their Luigi case. So I thought I'd better ;-)
I bought this brown/burgundy case when they were first offered so have been using it for I think its been 6 or 7 years, looks very 'hand-aged' now. It actually 'improves the grip on an M-series', that statement says something. Adds a bid of protection, especially if you have 2 cameras hanging on your body in some configuration, looks nice, and doesn't bulk-up the camera either. Film changing is a bit slower of course, and if I use the self-timer needs to come off, but then I need to get to the tripod socket usually then also. Personally I wouldn't get the 'hand-grip' model, adds too much and not needed.
I do like the straight two tone army green and burgundy strap that I bought from Artistsan & Artist in Japan ( no metal, body protector lug ring pieces, and ideal for me as its longer, and makes a quite beautiful combo I think.