there's digital Leica M8, which IMO doesn't count as a "real" leica and the pictures are worse than from canon.
Their wide angle lenses are awesome
They don't have mirrors, so the wide angles are cheaper to design
If you buy new, every little scratch on a leica body costs you 100 bucks
If you buy a user, you don't buy it, you borrow it. You sell it for as much as you bought it in the first place.
There's too much myth and mystique around the cameras. They break, the repairs are costly and at a minimum of 300-500 bucks.
They are very easy to focus in low light even with wide lenses.
If you want a leica experience, buy yourself a FED2 with a lens from Ukraine. They go for 20 bucks plus 20 bucks shipping.
There's two mounts - threadmount M39/LTM and leica M which is a bayonet mount.
The leica M bayonet is the later leica mount and the patents for it expired in the late 90s.
When patents expired, cosina/voightlander started making "bessa" rangefinders and a whole range of cool modern lenses, which are better than L line and cheaper too:
All full frame, sharp and with zero distortion, but heavy vigentting
12mm heliar f/5.6 for 500 bucks
15mm f/4.5 heliar for 300 bucks
28mm f/1.9 ultron
35/1.2 nokton for 700 bucks
There's also a zeiss rangefinder made in japan, goes for a grand which offers a awesome rangefinder.
A lot of the shooters who actually used both leica systems and bessas agree that the new voightlander glass is as good or better than leica.