To add to it
this person also says: "an annoying bug (at least, for me this is a bug!) introduced in Reader application of firmware 1.5.0, i.e. the fact that the chapter list of Go-To menu just consider the first-level items of the table of content. With this modified version, the chapter list will consider all items up to level 3 (i.e. the same behaviour of Reader app of firmware 1.4.x)."
I'm not on 1.5.0 so I can't test, but sounds like 1.5.0 is overall good, but they couldn't help themselves to take some good stuff away.