I have not cared for the Fate of the Jedi series, Apocalypse even less so, for a few reasons.
Abeloth. She sucks. Just plain sucks. When I read anything involving Abeloth I am put in mind of a lesser and much lamer version of a Lovecraftian Horror like Cthulu or a 40k Chaos Daemon, except they are actually frightening where Abeloth is not. And the Lost Tribe are equally poor villains, yet another group of Jaws.. I mean Sith, that keep coming back no matter what. They were never a threat to anyone really, the Yuuzhan Vong were a threat, compared to them the Lost Tribe is merely an iota of danger. I never had much hope for either of those two but sadly neither of them proved to be anything of real interest.
The Ones. I hate the Clone Wars cartoon with a passion, and now its weak material is being dragged into the mainstream books? No I do not like this at all. The book series should be able to carry itself rather than rely on material introduced by a kid's tv show. What would have happened if the Clone Wars hadn't introduced that drek, this entire book would require a complete rewrite. I wouldn't have minded a brief allusion to them but the entire plot hinges on something from another, and even worse, series and that is not a sign of a strong series to me. Plus absolutely nothing of The Ones was mentioned in any prior books, so it felt as if they just added all these Clone Wars links for the sake of advertisement.
Ben and Vestara. The one element of this series I found really interesting, which was marred by Jedi acting hypocritical and paranoid and by the creepy abusive turn the relationship took in Ascension. And of course this book continues it on in a disappointing manner, but I have not given up hope for this pairing, and I doubt we've seen the last of it either which is the one good thing about this element of the book. It didn't kill this pairing permanently, though not for lack of trying in this reviewer's opinion.
On the whole I disliked most of this book but while the plot is disappointing, the character development and resolution are equally bad and the links to the Clone Wars are just disheartening, the book itself is not badly written. Denning is a good writer, and the ending to a series like this is not something that he can just write on his own, others contribute to it and votes are taken on how certain things end so I place the blame on the entire writing team for this unsatisfying series. But there are a few good moments in the novel, sadly they are few and far apart and do not make up for the poor fare that was the Fate of the Jedi series.
I will keep an eye out for whatever comes next as while I do not care for how this series went, that is not to say I won't like the next one. As long as its not about the freaking Sith again, they need a damn break from them.