Just tried gMTP, works as it should. Siply install it from Synaptics of Application Center and see Multimedia-->gMTP in the system menu. To some degree, it is sufficient to manage the user content on the device; you don't need adb for that only purpose.
Note that I also have necessary settings in ~/.android/adb_usb.ini and in /etc/udev/rules.d/51-android.rules (I think you too, once you can see the device in adb.)
Also look Wiki for "Media_Transfer_Protocol" for other options. If you have Kubuntu, it will probably work off-the-box, with the above two files.
and manage the /storage directory by hand.
I wonder, has anybody ported MC onto this device?