I have read a fair number of books on cosmology and related subjects over the last couple of years, but I'm afraid to say that this was easily one of the worst ones. The author's main goal seems to be to approach the current mainstream theory - Big Bang with inflation - in a critical way, and suggest alternatives; the one he likes most is Steinhardt and Turok's ekpyrotic model, in which our universe collides with a parallel "brane-world" every trillion years or so, giving a cyclic universe where the collisions are the events normally called Big Bangs.
This is all fine as far as it goes, but Clegg does a terrible job of explaining the story, making frequent mistakes both with the history and the physics. For example, his account of how Hubble, Lemaître and Eddington interacted to produce the first tentative account of the Big Bang is almost completely incorrect, and his description of inflation leaves me seriously wondering whether he understands how it's supposed to work. I hope Steinhardt and Turok are taking the pragmatic view that all publicity is good publicity; it would be easy to slip over into feeling that, with friends like this, who needs enemies.
If you want to understand the issues around inflation and the ekpyrotic model, which I at least think are very interesting, I recommend reading Guth's The Inflationary Universe
followed by Steinhardt and Turok's Endless Universe
. If you'd like an authoritative account of the history up to circa 1970, Kragh's Cosmology and Controversy
is excellent. If you're looking for an entertaining popular account of the Big Bang, check out Simon Singh's Big Bang
, which is better written and more fun. I honestly can't think of anyone who would benefit from reading Clegg. It's just plain bad.