I have only read a smattering of Hogan's earlier work, but in all of it, I have found books to be strongly grounded in real science. Even when he's argued, as in The Legend That Was Earth, that modern Western science has become moribund beacuse it's so tied to orthodoxy that it's unwilling to accept any evidence that contradicts the orthodox theory, he's managed to bring me along quite willingly. I was, therefore, bitterly disappointed to find that the "scientific" basis of The Anguished Dawn starts from the crackpot theories of Velikovsky and builds on them, in the same vein, to a height of silliness that even Velikovsky would have found laughable. I almost stopped reading the book after the first 50 pages, but I had reasonable hope that a hard SF author of Hogan's stature was just playing with the reader at that point and he would make it all sensible in the end, and he'd also given a few hints of ideas that were interesting.
And by the time we got to the end of the book, there had been a number of ideas that were interesting and thought provoking. He shows us a way of running a society that's a refinement of the one he showed us in Voyage from Yesteryear which I find very attractive, and further that I actually believe might be possible in a modern world where technology has made material wealth plentiful, and he has some spiritual philosophy that is genuinely interesting to think about. He also includes a few bits of science that aren't tied to the loony cosmology that are interesting. And he wraps it up in a plot with enough action and excitement that Hollywood might be interested, even though there aren't really that many actual explosions.
This really could have been a fine book; he could easily have modified the plot to stay within the bounds of accepted cosmology and still had a vehicle for the social exploration, and if it wasn't as compelling a platform for the spiritual exploration, at least it wouldn't have been tainted by the bogosity. If you need to start from Velokovskian ideas to reach a spiritual conclusion, it's not a spiritual conclusion I'm very interested in.
Still, while I certainly cannot wholeheartedly recommend this book, I cannot wholeheartedly disrecommend it either. I would love to be able to talk to other people about some of the ideas in it, so if you can make it past some really silly cosmology from a writer who definitely should know better, do read it. 6 out of 10.