I know Linux does not play well with the MTP method that new nexus devices use.
I do have it working on my Linux Mint 13 laptop though.
When calibre detects my device and reads the books off it. it takes about 8 minutes.
from my debug log I get the following
MTP: Filesystem metadata loaded in 474.418 seconds (11989 objects)
it seems to be scanning the entire storage area. I see it listing every epub, pdf, html, pdb, and cbz file on my phone.
Is this behavior correct? does calibre scan everything? for every format it understands? if so why is it taking so long? When I open up the nexus4 folder it seems to load and move things as fast an anything else.
once I have unmounted my phone and I recconect it later. Calibre does not see it. I have to resart the udev service and then calibre reads my phone again.
I suspect the linux implementation of MTP is the cause of all this but I'm posting this in hopes someone has an answer and to help make calibre better