I've emailed them to ask for changelog information, and queried when this function might be coming back. For now, I've just downgraded to the previous version (which can be found
here if anyone is interested)
I've got a feeling taking that function away was intentional - for example if you try to load a book that crashes your reader and it resets, it'll go into a loop of trying to open that same book and crashing. This way, at least if there is a problem you're back at a usable menu.
I tend to keep all of my books on the SD card, so if something were to crash and it goes into a reboot loop I can just pull out the SD card and it won't try to open the corrupt book.