The kind people at Luminous Landscape have an article about a Leica factory visit in Solms, Germany (by Nick Rains).
These [Leica S2 and M9] are hand made products – quite literally. It’s why they are desirable in the first place and the process can only proceed so fast. I’m told it takes 8 hours to assemble an M9 body and having seen the care and precision with which they are assembled, I can certainly believe it.
This should explain why the quality is at the top along with the price.
Lloyd Chambers wrote an open letter to Leica:
The M9 felt like 2 year old technology the day I got it, with many disappointments.
And yes you are allowed to bad mouth Leica. I believed that the M8 was a mishap – evidence that Leica didn’t really know what to do. Apparently the M9 is too. And very expensive. Chambers has already written very extensively about the M9 (sorry, paywall).
And I have read a lot of praise about the Leica M9 too.