Read position in feeds
The big change in this version is bringing Boost's preserved read position to chronological feeds. This can be enabled from the Feed Settings page (top right button on the Home page), and is limited to premium subscribers.
When enabled any feed that returns posts in chronological order, with allowances for a few posts being mixed up, will automatically open the feed to where you left it.
Thread controls
Two smaller additions, both in the more menu (...) on any post. Mute Thread hides further updates to that thread from your Following timeline. Unroll Thread shows all posts in a thread individually in your timeline, so you can follow updates live without the full thread showing for each update. Unroll shipped in the first version of Boost Blue, but it caused enough bugs that I pulled it until I could get the experience right.