Interesting test results over at DxO Labs where they test each camera for image quality (technically, image sensor and RAW performance). The Leica M9 boasts the first full-frame image sensor in a non-DSLR body and a full-frame image sensor has generally meant the ability to take incredible low light pictures at high ISOs. Compact digicams, with their markedly tiny image sensors, usually fail this test (oh, they might use aggressive noise reduction to remove the noise, but image quality inevitably suffers).
DxO Labs rates the Leica M9′s Low-Light ISO at 884 out of 3572, which is a 24.7% pass — or fail, depending on your viewpoint. Overall, the Leica M9 image quality rates a 68.6%, which is higher than all compact digicams, higher than most of the entry-level DSLRs (which use a smaller APS-sized sensor), but lower than many full-frame DSLRs.
Of course, as its fans will tell you, this does not say anything about the Leica M9 [Specs], either on its quality as a photographic tool or its [or its user's] ability to take superb photographs.
Takeaways: Use tests as just another criteria to help you choose your photogaphic equipment; and, realize that there are many cheaper alternatives out there that can take as good or better image quality that an M9.
View the Leica M9 DxOMark results at: Dxo Labs.