Most of the suggestions you've had so far are well thought out. I have a few additional comments.

The Bessa rangefinder bodies use a metal focal plane shutter designed originally for SLR cameras. It's not quite light-proof enough for use without a mirror in front of it, so Bessa uses a secondary shutter to help keep out stray light. A metal shutter is louder than a cloth focal plane shutter, and the secondary Bessa metal shutter adds a little more noise. So the Bessa shutter is a bit noisier than a cloth focal plane shutter, definitely louder than a leaf shutter, but not in the same league as an SLR. I use several Bessas, as well as several SLR models and other rangefinders with leaf and cloth shutters. The Bessa shutters are not as loud in comparison to other cameras as Allan (kaiyen) implies.

Rangefinders also have the advantage of a very short lag time between pressing the shutter button and the frame being exposed. You don't have to wait for mirror travel, and for fleeting people shots, this can be a definite advantage. SLR mirrors and their noise preceding the exposure can also allow enough time to trigger a reaction in the subject that you might not want.

Allan (kaiyen) is right about handholding rangefinders as well. I have a shot with a Bessa T and 21mm Voigtlander-Cosina lens made at 1/4 second handheld, and you can count the threads in my son's t-shirt from 4 to 5 feet away. (I have an SLR that can approach that, but it has a rarely-implemented cam-driven mirror design that doesn't slap, and a heavy brass chassis with good inertia.)

The view finders in rangefinders can be excellent. You are looking much more directly at the subject than with an SLR and you can see the surroundings outside the frame as well. I love the 1:1 finder in the Bessa R3 (others do not) for the fact that I can leave both eyes open and see the framelines floating in the world in front of me. Rangefinder focusing with a quality camera like the Bessa and other brands is also very snappy and fast.

As FrankB mentions, one big advantage of rangefinders for people photography is the fact that you still see the subject at the instant of exposure. The shutter lag and disappearing image in an SLR may leave you wondering whether or not you caught that fleeting expression (until you see processed film). With a rangefinder, you have a much better idea of exactly what you got at the instant of exposure.

For macro and telephoto use, I would still use SLRs.

As others have said, after taking into account the physical limitations of the hardware, it's what's a few inches behind the film that really counts.

Lee