I am currently reviewing it chapter by chapter for my Patrons.
Firstly, the production values are just glorious. The handouts are amazing (though not as amazing as the HPLHS set - those are out of this world), and the books have great art throughout.
The intro chapter really sets the scene, doing a great job of encapsulating the entire campaign and the prologue in Peru does a good job of introducing Jackson Elias in a manner that makes him a person rather than a bit of a gaming meme. He never becomes the focal point, and gives good reasons as to why the investigators eventually consider him a good friend. As per every edition since the Complete version, the Australian chapter is part of the canon storyline and is included.
It's also worth mentioning that Pulp Cthulhu gets proper treatment here - not just two pages at the end - it is throughout the book whenever appropriate.
My hope going forward is that nothing more is added to it. I could envisage it becoming a bit of a bloated woman of a campaign if they extended it further.
I think it would be great if Chaosium basically said "right - that's it. Masks will not be changed any more than this. This is 100% the definitive edition" as a kind of tribute to the late Larry DiTillio.