Everything Traviss points out about Halsey is true, and she doesn't present Osman, Parangosky, et al as morally superior. They make it abundantly clear, for instance, that Parangosky is nailing Halsey because she'll get personal satisfaction from it, and because it's politically expedient to scapegoat her for everything. Black Box's hatred of Halsey is essentially forgotten self-hate from his donor mind (whose suicide note basically says "yeah she was evil but we helped her every step of the way.")
Where I do think people have valid points complaining about her writing though is that we never really
move on from Halsey. The impact of the Spartan program is a clear thread throughout the books, but we really don't need to hear it over. and over. and over. I said this when
FUD did its podcast on Mortal Dictata, but it felt like "Mortal Dictata" was the story Traviss wanted to tell about Naomi, and the other two books were 343 saying "well we want to tell some new stories post-Halo 3 and also we need to wrap up Ghosts of Onyx.
So not bad, quite good in places, and character-focused rather than action-focused, which if you're into that style is better than Nylund, but there's definitely some fat in these books that has less to do with length like The Flood and more to do with construction.
Traviss also suffers from having to close a plot thread that could really have used its own book (Ghosts of Onyx).
Shirley has a much less encumbered template to work with so I'm excited to see what happens there.