I checked out an MP3 audiobook and tested the sync feature with three devices -- Nexus 7 v2, Fire HD 7, and iPod touch 4 -- and it works nicely. The audiobook must be downloaded on all devices you wish to sync.
A bonus feature for iOS devices only is variable-speed playback -- .5x, 1x, 1.25x, 1.5x, 1.75x, 2x.
Contrary to an
earlier post I made, this upgrade will have a positive impact on me. I stand corrected. The audiobook sync is a great feature.