If you haven't, I really suggest that you read BR: Kragnos. IMO, it is by far the best narrative in an AoS mainstream book so far. I know the reactions to the summaries have been mixed. But summaries betray the quality of the narrative. BR: Kragnos is mainly narrated from the viewpoint of normal humans in Excelsis. This is so in chapter 1 and 3, which are far longer than chapter 2 (mostly Skragrot point of view). This is far better than all previous books. Teclis takes places mostly from a godly point of view; the lowest it descends is either to Lumineth heroes or Mortarchs. And it feels much less grounded. I would say the same about dimensions travelling narratives in Be'Lakor and Morathi. Here, Excelsis and Ghur really shine from a grounded point of view.
Chapter 1 is essentially a narrative of inner strife in a city that knows it is marked for likely doom. Although nothing really important happens in it, it is beyond even City of Secrets in achieving that narrative.
And chapter 3 is the story of the siege of Excelsis. I think no siege had been so well done since the fall of Altdorf in End Times. As a battle, it is arguably a more spectacular narrative with the combination of full waagh siege of a massive city, with a fleet attack, and an inner catastrophe taking place at the same time.
The resolution to the most important parts of the plot may sound lame when written as a summary. Grodrakk joining Kragnos isn't easy to explain - it is hinted that it is the effect of the Bad Moon, but it feels like a deus ex machina. The final victory of Order feels less of a deus ex machina and introduces, yet again, Morathi as a major player. But anyways, I think any warhammer fan would do himself a favor by reading this book.
As to the Epilogues, I did not find them as good, except for the now explicit confirmation of Grugni's return and direct involvement and stuff. The Nagash-Teclis exchange is getting old; Be'Lakor - talons of Slaanesh feels irrelevant; Kragnos is just an introduction of the Kruelboyz. But Morathi's "judgment" and Grugni's interruption, though not a great narrative, points nicely to things forward.
Oh, and I remember that when AoS was launched, there was this rumour that Lizardmen were turning to dragonkin. Guess that will very likely happen now. Interesting times!