TL;DR: There were some good bits of lore and mechanics, but this book reverts to bad, '1st-edition-ish' philosophy far too much.
So, let me start off with saying the things I did like, and why I'm giving this two stars rather than one.
There are good sections. The Orisha's section is awesome, predominantly because it essentially mocks the premise of the rest of the book. The Deva have some really cool and well-done members in there, and while the Theoi are questionable here, Echidna is great.
The mechanics are good, too. The new callings are nice, there's some good antagonists and other new Storyguide mechanics that I enjoy. If mechanics is predominantly what you want, this is definitely a solid recommend - although if you're a player and not a Storyguide, seeing as the new callings are the only parts that pertain to you, you might want to wait for Demigod as I hear they'll be republished in that.
The Internet Trolls are incredible.
There's a few parts of the book I won't comment on, such as the Kami and the Manitou, simply because I haven't got enough knowledge about those cultures.
But now, the stuff that was bad, and that I think I can comment on.
The Tuatha Dé Domnann are just... inaccurate and insensitive. The implication that Balor caused the Potato Famine is just... that wasn't anything to do with supernatural. That was the British being horrific.
Belenus and Cernunnos don't belong here, they're the gods of long-dead continental European religion and are part of the Nemetondevos according to another book in 2e. Admittedly these other 'versions' are acknowledged, but it just... doesn't sit right. It feeds the 'Celts were all one culture' concept that many have. And that concept is wrong. Not only that, claiming Cernunnos is the Horned God of Wicca (as in, this Cernunnos, not the idea that an old remnant of the power that was Cernunnos has somewhat been revived by Wicca as that god - that's a cool concept, this isn't) is really dodgy when, while he may be the most 'good' amongst these guys, is still associated with the 'evil side' of a pantheon. These are bold claims about what you claim to be the god of a living religion.
I can't really comment much on the other Titans of the Tuatha. But, as far as I know, one of them we know next to nothing about, and the other's writeup seems to imply Ireland's in the UK. So yeah.
Final thing on the Tuatha is something I didn't notice the first few times I glanced through, but is honestly one of the most grievous things done to them. Indech, who was the King of the Fomorians, who would have been an incredible choice for a Titan instead of, you know, the Gaulish Gods, has been turned into Frankenstein for the sake of having an excuse to put the Monster in. If you want the Monster, as a more modern story to add to the game, invent someone to create it. Hell, have them be a sample Scion of Prometheus (and writeup Prometheus) and really go full-on with the 'modern Prometheus' vibe. I'd love that. Don't appropriate someone with nothing to do with any of that.
The Aesir are weird. Nidhoggr is written as if he has a rivalry with the Dragon Níðhöggr, who I assume is coming in Scion: Dragon. A few reasons why this is confusing: first, IIRC, Dragon is intended to be optional. A potential addition to your games if you want it, portayed like the Nemetondevos, Teros, and the upcoming Masks of the Mythos. I honestly quite like the idea of Dragon, but having lines of this book, which is supposedly part of the World's mainstream 'canon', refer to it is odd. The second reason is that if you want a rival for Nidhoggr, he has one. Right there in the myths. The unnamed eagle, who sits at the top of Yggdrasil. They send insults to each other via Ratatoskr, the squirrel. But the eagle is only briefly mentioned, and the squirrel is completely absent. Also, the whole thing about spelling being an argument, albeit a somewhat sarcastic one, about Níðhöggr being older, is a bit odd.
Ymir's dead, so not a threat. Reviving him... like, it's somewhat understandable, but not including, say, any of Loki's children (I'm aware Jormungandr and Fenris are more animals than logical thinkers, but Hel could surely fit in) and deciding to revive someone long dead... it's an odd decision. And, come to think of it, the Monster purview works fine for more 'bestial' Titans so yeah. What the Hel. Throw in at least one of the children of Loki instead. (And yes, I know they're mentioned, but none of them get a proper writeup.)
The Netjer have problems, but not really any more so than their godly counterparts' writeup in Hero. Aten is better than he was in 1e. That's not saying much, admittedly, but overall, I find his writeup okay. Apep/Apophis is another victim of the Dragon references, but it's dealt with a bit better. Isfet should probably be a Primordial, not a Titan, but I can deal with this. In fact, the writeup says she has the 'Primordial' calling; I'm assuming that typo was caused due to the writer having similar ideas to me, and meaning to write 'Primeval'. I should submit that to the errata. Finally, in the art, Apep is depicted with a cobra-like head fan, and as far as I know, he's not really depicted like that in Egyptian art. Just a plain old giant snake, no flourishes.
That's about all I can talk about with my knowledge. Oh, and looking back, the description of merfolk... like, the vicious concept presented here is fine, but there are also mermaid tales that do cast them as beautiful women, or even men, luring people to their doom - or perhaps not, perhaps falling in love with them and taking them back into their home under the waves. The idea presented here kinda contradicts the 'All Myths Are True' premise.
So, a final thing. Years ago, a young me stumbled across Scion First Edition, and was fascinated. Here was a game that was inspired by the tales I loved, and would allow me to play in worlds like those written about by Rick Riordan as a child of the gods. I plunged in, and expected the people making the book had done their research, and I took in a lot of misconceptions about the gods presented.
Now, 2e is here. Someone in a similar position to me back then will probably go for it over 1e - it's more up-to-date, more revised. New editions are meant to be better, and 2e is better. It's balanced, and it's pretty well-researched, and on its failings in research, it still tends to be respectful. And so someone in that position won't find the awful ideas that were present then, and instead find what Scion 2e has done, and take that as the truth about these religions. And that is good.
But then that someone may find this book. And, seeing as the research and respect so far has been good, they think to themselves, why shouldn't this be the same? And they'll take it, and they'll be plunged into misconceptions in the same way I was, and they might not be as lucky as me and find out that what they read was wrong. And that makes me beyond sad.