This book is not set in the universe of Dark Light, Cosmonaut Keep, and the other books I've read by MacLeod. I haven't read all of his books, but as far as I can tell, this is a standalone.
It's nominally set in the far future, with some meaningful advances in technology and society, but on the whole the human society seems too familiar to me. I think I'd be less lost there than a typical person from a mere 300 years ago would be today. It's also a first-contact story, with aliens that aren't quite human, but more nearly so than they really should be. But that's all background, and while it tugs a little on the suspension of disbelief, it doesn't strain it, much less snap it.
In an era where most authors seem to write much longer books than they should, this one seems to suffer from the reverse problem. The pacing is reasonable at the beginning, but as the book proceeds, major events start happening so quickly that it becomes very confusing, and it's hard to really follow the characters when long stretches of time when exciting things are happening just vanish into the gap between chapters. I think this is why I don't identify strongly with any of the characters and at the end of the book, I don't care very much about where they ended up.
There are some interesting ideas in the story. A really bizarre space drive, and some philosophical implications and unintended consequences, that would seem more profound if the space drive concept didn't seem so improbable (or perhaps if I had better drugs). The most interesting ideas, really, are the ethical dilemmas and speculations the humans get into when they study the aliens. Most SF involving humans and aliens seems to assume, implicitly or explicitly, that humans are the superior species -- if not technologically, then ethically, or in terms of ability to succeed in the universe. We actually get a glimpse of how it might not be so; unfortunately, the real point comes in at the end of the book, where things are happening too fast for the idea to really be examined.
A pretty good read, with some interesting things to think about, but not completely successful; it seemed less coherent than his earlier work that I've read. 7 out of 10.