According to the foreword, Nokes claims that he wants to challenge the perception of Jane Austen as "an angel" and instead provide a fuller portrait of the author. Does Nokes accomplish this? Perhaps. Does he layer so much extraneous detail into this thing that it starts to feel outright stodgy? Sure. But does he let the actual perspective of Austen prevail through all else? ...Maybe.
The thing is: Austen is always going to be a woman shrouded in mystery. She was born one of eight children to a reverend, and grew up, like many of her siblings, writing little sketches and bits for her family to enjoy. It wasn't until 1811 that her first novel (Sense & Sensibility) was published and set her on the path of becoming An Authoress.
After her death, her family seems to have in many ways closed ranks in order to preserve the idea of a woman faultless and virtuous: Henry Austen's posthumously published short biography offers a glimpse at the shape of the woman who authored those books; Cassandra Austen pruned her sister's letters and removed anything she thought too revealing. At the end of it, we're left with an understanding of Jane Austen through the lens of those most desirous of protecting both her, and the Austen legacy.
So does Nokes truly undo any of that historic meddling? I'm not sure: there's a lot of information in this thing, and a lot of asides and examples of some of the other skeletons in the Austen closets (e.g., her cast-aside brother George Austen; her Aunt Leigh-Perrot's trial for theft), but it doesn't feel that much like a revelation about Austen herself, especially because so much of this is merely restating her itinerary and quoting her letters.
I also want to specifically call out how terribly this ends: Austen's final years (1816-1817) are a brief chapter, capped off with a handful of pages tying off a few outstanding threads (such as Cassandra's retaining the cottage at Chawton; Frank Austen marrying Jane's roommate / friend Martha Lloyd) but it doesn't do anything with the momentum built by the previous 500+ pages. Austen's legacy, her impact, her life merely tapers off as if Nokes was exhausted with the thing. (And this is also worsened by the introduction which spends so much time with Austen's parents' parents before anything even remotely Jane-based!)
A final complaint: there are so many Janes and Marys and Frannys floating about the thing that the latter half (once all the nieces and nephews and great-nieces and -nephews roll into town) that it's almost impossible to keep straight. Any context would have been extremely useful—but such a thing would also have called to attention the number of individuals who we get no resolution on. What happens to Franny Knight? What of the sour Mrs.J.A. (James Austen's wife nee Mary Lloyd) who so alienated Cassandra and Jane? Did Edward Austen Knight win the case for Chawton? I assume, based on Cassandra continuing to live there until her death, that he did, but.
Ultimately, this was a whole lot of information that goes to spaghetti noodles rather quickly.