I've recently purchased a Canon QL17 3rd generation and I have to say that I am loving this camera.
-Camera is unimposing (great for street photography)
-Uses a leaf shutter, making the camera quieter than the clack clack of an SLR
-It's a rangefinder (Oh, I do love my rangefinders)
-Light weight (great for my fragile, weak arms)
-Able to use full manual or use aperture priority, automatic exposure, or even full manual.
-Requires an outlawed mercury battery
-require a lens hood that is an awkward 42mm
-focusing is a bit awkward for the way I would hold an SLR due to the lever of some sort that juts out of the focusing ring.
But these downsides are all rendered moot once you actually get a hold of this camera and discover how fun it is to handle and shoot with this camera.
Here's a sample shot I took at the park: