I picked this up for free as part of a 3 for the price of 2 offer at Blackwell's in Oxford and I was delighted. It has made quite a lot clear to me that I didn't get before: what Einstein was trying to do when he came up with Relativity, how the current description of our universe (Big Bang, Inflation, Dark Matter, Dark Energy and a tiny, but non-zero Cosmological Constant that appears only to have cut in at round about the time that the Solar System was forming) seems pretty unavoidable, and why the cosmologists hate it (because it is such a Heath Robinson universe). The book won't be for everyone - Barrow doesn't shy away from graphs and equations - but if you've got say A-level Maths or Physics then you should be OK.
I think I spotted some editorial omissions where what Barrow says seems to be at variance with what I think he means. On the other hand, maybe I simply misunderstood what he was trying to say. In either case I don't think I can give the book the fifth star. But give it a go anyway.