Popular Photography magazine's website has published a hands-on review of the digital Leica M8 by a war photographer. Ashley Gilbertson is a freelance photographer who has been working in Iraq since 2002, and who took two Leica M8s to Iraq.
His experience with these cameras was highly satisfactory, saying: "In my opinion, Leica has created a perfect transition to digital from its M-series film cameras. The Leica M8 is just as small, almost as durable, and as easy to use as its film predecessors, and it yields an incredible file in both size and sharpness. As someone who has hated the transition from my old Leica kit to digital, the M8 is my ideal camera to marry the elegance and robustness of the M series with cutting edge digital technology."
I'm on the lookout for a small backup for my Canon behemoth, and in this case the Leica would obviously be a replacement rather than a backup...so I'm interested in gleaning as much hands-on feedback as I can get. I know that the Leica M8 has its quirks such as having to fix an IR filter on it (supplied free by Leica), and its settings have to be carefully tweaked before using it...so hardly a camera for absent-minded photographers. However, some pros swear that its image quality is incomparable.
Here's the Popular Photography article on the Leica M8.