I really liked my PocketBook InkPad Lite. After the one-time firmware update, I put it into airplane mode permanently, and always just updated DRM-free books on by plugging it in as USB Storage, and `rsync`-ing `~/doc/` to it.

The update script was pretty much this (on a laptop set up not to automatically mount removable filesystems):

    #!/bin/sh -x
    DeviceMountPoint="/media/pocketbook"
    mount "$DeviceMountPoint" || exit 1
    cd ~/doc || exit 1
    rsync -crltv . "${DeviceMountPoint}/."
    Status=$?
    umount "$DeviceMountPoint"
    exit $Status

And the `/etc/fstab` entry was something like:

    /dev/disk/by-id/usb-USB-FS_PocketBook_MYSERIALNUMBER-0:0 /media/pocketbook vfat user,noauto 0 0

Ditto. It's also significantly lighter weight than competing readers (at least when I bought mine), has physical buttons, has color models, and has really good battery life possibly because it runs a custom Linux instead of Android.