Okay, I admit it, I was driven to check out the Leica digital rangefinder cameras because of the great time I've been having and the excellent photos I've been taking with their little X2 point-and-shoot! (See my X2 review if you'd like.)
The rangefinder paradigm is admittedly not for everybody but if you ever fell in love with shooting 35mm film on a Contax or a Zeiss Ikon, the M9 might be just the perfect digital camera for you!
The body is solid and the build quality is unequaled. A perfect fit in the hand with just the right amount of heft, it's great to know that highly engineered objects of this kind of precision and quality are still being made! You'd be hard pressed to find any plastic on this camera! Let me just get this out of the way now: The Leica does indeed cost a bundle but is worth every penny. Also, for what it's worth, the new M-E version is $1500 cheaper than the M9 though it is, for all intents and purposes, identical. Used M9s are even better deals, especially if you find one with a low shutter count.
I shot Canon gear for years and finally, after some considerable time hands-on with Leica rangefinders, I've completely liquidated my 5DmkII and a bunch of Canon "L" lenses. The M9, a spare battery and three lenses all fit in a tiny camera bag that only weighs a few pounds! Compared to the bag I used to lug my DSLR and lenses around in, this is practically effortless, plus it's much more discrete to carry as well as shoot. The compactness of the M9 is unrivaled. People don't react in the same way to the M9 as they did to my huge DLSR - they're more relaxed and comfortable. This thing just doesn't look that imposing. ;)
The Leica M lenses are simply phenomenal! They're extremely sharp, even in the extreme corners (where my Canon L glass didn't fare so well). These lenses are sharp and contrasty even when shot at wide open apertures and that even applies to the wide-angle lenses! The 50mm Summicron and 35mm Summilux have been excellent partners for this camera, though my favorite is the 21mm ultra-wide Elmarit as it's helped me to capture stunning landscapes and seascapes in contrast and clarity I could only dream of before.
The CCD sensor in the M9 and the new M-E buck the CMOS trend of most modern digital cameras and certainly affords the Leica a unique image signature that is absolutely lovely. Overall, I've found it to be very film-like. From my own experience, I've noticed that the M9's files require much less post-processing than my Canons or any of my other cameras.
If size and image quality are paramount, and you like the rather considered process of using a rangefinder with a manual focus lens, then maybe the Leica M9 or M-E is a good fit for you. It's certainly worth trying as it is so radically different to a DSLR. Though a good photographer can take a great picture with just about any camera, a superb one like this certainly makes it a lot easier to get the results and consistency I want.
Rent one, see if you like it, and if you do, save up and buy a used one from a reputable dealer like I did. :)
I've attached a few images below - click on them for larger versions: