The M5 is not so much maligned as it is ignored. I've never owned one, but in the '80s I did use one for six months, owned and loaned to me by a friend who had moved overseas and I think, wanted a safe home for it and his Summarit 50/1.5, and I found it to be an excellent camera, if rather oversized for an M of its era and with one quirk that annoyed me - the metering system.
As I discovered after a few shoots, the meter was a sort of button stuck on he end of a rod, which came down from the top part of the focusing system of the camera every time I wanted to take a photo. In retrospect it was most likely a very fast process, but at the time it seemed to take forever, and as I was then involved (for a very brief period) in trying to get some good street shots, this behemoth was just too slow to be of any use as anything other than a posed snapshot Leica, and really, if truth be told, who needs one of those?
Fast-forward in time to nearly forty years, and now, with most of us Leicaphiles (or -phobes) being much older, along with the cameras, the M5 seems to be a very genteel and almost gentlemanly (or ladylike in some situations) film shooter. I for one would be happy to own one if prices were not so damnably high on them.
So I make do with my collection of Contax G1s and superb Zeiss/Kyocera lenses, but this is speaking heresy, so I'll say no more.