I read this book a few months after getting through A Brief History Of Time and Astrophysics for People in a Hurry and it has some similarities - but it was longer than either of them, and also seemed to repeat itself a bit. I recall reading somewhere (maybe in the forward?) that it was really a collection of self-contained essays that was massaged into a novel - and I guess I'm saying that it showed, though it wasn't done poorly.
Since I had just read the other two books, I'm not sure I got much out of this one, but it was still an interesting read.
Neil is a good writer and sprinkles jokes and interesting facts all over. I especially like how he describes really astronomically large numbers (a billion billion ... billion whatevers). I also enjoyed the descriptions of how some things were learned, or could be personally observed using backyard methodologies at times.
It's dense writing - you really need to read it rather than just skim it. I tended to read it before going to bed, and that implies that I was drowsy at times - maybe not the best way to tackle this.
Much of the material was better handled in the other books I mentioned above (though that's not to say this book didn't do them justice).
This says more about me than the book, but there were plenty of sections where, after finishing a chapter, I'm pretty certain I couldn't accurately regurgitate what I had just read, though while reading it I thought I was getting it.
Maybe don't read this and read A4PIAH or ABHOT instead. I give it a 3 out of 5, which is still perfectly respectable.