I'm actually more split on my impression of this book's quality that the relatively high 4/5 I gave it may suggest.
I like the updated history of the Sabbat that the book provides and the alternate take on the sect's changes/growth up to and around the time of the events of V5. Working the Sikorsky/Galbraith affair into the sect's most recent turning point was a nice touch, and the look at the sect in the fray of the Gehenaa as well as how it can feed back into activities outside that arena is rich with possibilities.
In regards to some of the mechanics that are introduced, I'm less impressed. The return to clan-specific disciplines for the Tzimisce and the Saalubri Antitribu seems notably misplaced in the current edition, especially given the use of an Attribute + Skill framework for power dice pools that is absent from every other discipline in the game (it's obviously not a hard fix, if one considers it a problem, but it does make me wonder how much thought went into them to begin with). The Sabbat predator types in the book come off as low-effort paint jobs for existing predator types from core, with the exception of Sorority Sister, which I find to be different enough in its approach to hunting from the Scene Queen, despite their similarities, to bring something a bit distinct to the table.
Most egregious in my opinion are the gaps and ambiguities in the Path of Enlightenment system that the book offers. The preceding section on Sabbat in V5 regarding tenets obviously seeks to address the matter of stains in Sabbat Chronicles and when/if they should come into play, though its statements about automatic stains is curiously focused on murder and torture, which may or may not actually be stains depending on chronicle tenets; as far as actual automatic stains go, the list largely consists of using blood bonds, embracing mortals, varying degrees of harm to Touchstones, stain accrual that's baked into the use of Oblivion in general and the use of specific discipline powers. The general advice to use such stains 'sparingly' technically applies to these default stain triggers, though given the focus on things that aren't actually automatic stains it isn't clear to me that they're what the author had in mind. Even then, however, the book offers no real insight as to which of these sorts of automatic stains or more or less appropriate for Sabbat chronicles, and even accounting for possible outliers that aren't included in the list I provided above, it wouldn't have taken more than a paragraph or two to adequately address this for the majority of cases that turn up in the V5 books thus far. The matter of automatic Humanity loss from diablerie isn't addressed at all, though I think fair reading of the rules presented is that Sabbat who have yet to transition to a Path of Enlightenment remain subject to it while those who are on Paths do not (though it may conflict with the Ethics of their Paths and thereby still merit stains depending on the circumstances). Insofar as automatic stains do apply, the rules for Ethics associated with Paths as replacements for Convictions ironically render them worse at protecting against such stains than Convictions from Humanity since in contrast to the lost Convictions, the Ethics only reduce the total number of stain incurred by one at the end of a session rather than mitigating stains per action. This leads to the almost comical scenario where in order to maintain one's Path rating, the character must succeed on a Remorse roll to feel bad about taking actions that may well be explicitly endorsed, or even celebrated, by the Path they have committed themselves to. Moreover, it's not even clear how many of the Ethics apply to individual characters, which is important not only for their role in stain mitigation, such as it is, but also as a source for stains when characters act against the values that they espouse (and on that note, it isn't really clear what "violation of ethic conviction" is supposed mean on the Violation/Stains table given that the Ethics replace Convictions to begin with). We know that at least one of the Ethics will apply to characters, since that's covered under conversion, but beyond that it isn't clear when or how characters choose additional Path Ethics and it isn't even stated that characters starting on Paths, and thus having Path ratings of 6 from the get-go) choose more Path Ethics than those who are freshly converted.
Hell, as far as conversion goes, it doesn't even provide any information on how a character would go about increasing their Path rating at all; possibilities such as basing the experience cost on the costs for increasing Humanity in core (though that'd obviously be problematic with default experience reward suggestions unless the goal is to spend most of the Chronicle as a near-wight or likely Wassail well before it ends), using the rules for Projects, or simply roleplaying Path advancement come to mind, but even that sort of preliminary spitballing/handwaving demonstrates more thought on this subject than anything that actually made it into the book. I consider this a serious shortcoming given how important the Paths are to the identity of the sect, especially considering how much the author seems to think the book is worth.
To wrap this all up, as far as narrative and thematic elements of the book are concerned, I'd rate the book as a 4 or a 5 out of 5. Mechanics-wise, it slips up enough that I'd rate as a 3 out of 5 (if looking at the rules for Paths alone I'd bring it down to a 2 out of 5). Given that this review is for other people, I settled for an overall score of 4 with the expectation that others may not share my issues with the mechanics, or at least not be as disappointed with them as I am.