The 3.75 stars rounded up had more to do with the plot and other characters instead of the supposedly main ones (Tohr and Rosallyndha/No'One/Autumn - imagine that, 3 name changes in a book!).
Throe/Layla/Xcor was a potential to turn into a story. Alas, both males were of BoB variety instead of BDB. And Lassiter was a welcome character with his rather attachment with the tube's series. I'm sure there'll be more on Assail too, he's being an unpredictable island this time.