I'd give this 3.5 stars if GR allowed half stars. There were parts of this book that were brilliant, and parts that were intensely annoying. This is the first book I've read by Charles Stross, and I'm frankly unsure whether I'll dive into another Stross novel any time soon. I liked the overall plot and the ideas; human civilization evolving towards a Singularity, and what happens to the posthuman offspring. But the story leaps about erratically, sometimes skipping years or decades and light years at a time. Human civilization is jerked forward, things happen, and then the whole civilization jerks forward again, and each time we have to reorient ourselves and figure out what's going on (and more importantly, why we care -- the continuing characters change between instantiations almost as much as the world does). The writing is dense and full of obscure references, and I'm not a fan of novels written in present tense.
That said, I'd still rate this as a brilliant, original novel worth reading, especially if you are into cyberpunk and transhumanism. However, it's not a quick, easy read, and if you are looking for a sci-fi "adventure" with characters who have easily identifiable goals and motives, this isn't the book for you.