The PDF Table of Contents bug is fixed, which, coupled with reflow, is a strong reason for me to want to keep using it.
Font size selection is the same as the jetBook is you are reading something other than ePUB/PDF. In that case, the Libre uses FBReader. For ePUB, you get varied zoom levels. For me, "200%" seems a bit big and "150%" a bit small. 175% would be perfect, but I just read with 200% and more page turns.
Arrow keys do not turn pages (perhaps they do in FBReader, but I don't have any non-ePUB to check right now). Funny--I didn't notice, because I am in the habit of using the buttons in the lower left since I read quite a few PDF's and that's what they use on the jetBook.
Page numbers on the side is irritating, but I guess this is what ADE users have been putting up with for a while. Just ask JSWolf what he thinks about it.