The principle behind this plugin is great. Unfortunately, it's let down by some terrible usability.
1: Moving items around within a series seems to be a hit and miss affair. If you try to move a part into a position already occupied by a part, sometimes it works, and the other part[s] shuffle up to make room. sometime the part yo moved gets assigned a number at the end of the stack. It seems completely random.
2: By far the biggest shocker though is that, when you choose the "Quick Edit" button next to a post, the existing series info isn't loaded into the editing form, so you either have to re-enter it each time, or your series info is wiped out when you save your edits.
I want to like this plugin. In theory it's the best way of organising a series of posts into something like a book. However, the clunky usability and the fact that, having spent ages configuring a series, you are liable to have it all come crashing down like a house of cards if you have the temerity to "quick Edit" any of the posts in that series makes it completely unusable for me.