Film Leica is crap. I regret buying one. I got one because in my deluded mind I thought: as a photographer I MUST have a Leica! It will make me feel like an oldschool photojournalist.
But it is a waste of money.
1. The sharpness of the expensive lenses is wasted because at the end of the day it's 24x36mm film. The same film used by compact cameras. You might say that because of the small film size every bit of sharpness you can get counts but you just won't get much resolution out of it anyways. Unless you also buy a professional scanner to extract the full detail of the film.
2. The viewfinder is inaccurate. The framelines are calibrated just to one distance which means that you will often not make full use of the frame and will have to crop an already small film area. The closer your subject the more parallax there is. Ever seen one of those photographs where something in the background aligns with the foreground? Good look doing this with a rangefinder. Oh and last but not least you won't be able to see the true depth of field.
3. (Only applies to anything but the M7) Lack of AE means that you will have to meter ahead or you will not be able to react to spontaneous photo situations.
4. (Personal) Because it's so expensive I am always aware of it and afraid to damage it which makes me a bit insecure and too careful.
Using my cheap $100 SLR is more fun in the end and gets me better photos.
Better invest that money into a medium format camera.