The definite article in the title seems a little hubristic. I don’t know if this is the definitive biography of Shakespeare — haven’t read any of the hundreds of others — but I certainly enjoyed it.
I don’t know if I completely trust Ackroyd as a historian; it’s probably unfair, but I just get a nagging sense sometimes that he’s a bit too fond of a good story. He has clearly done a ton of research, though, and as you’d expect he’s very good at providing historical context. And he writes well.
There’s a perception, perhaps, that we have very little historical record of Shakespeare other than the plays themselves, so if anything I was surprised by how much material there was: legal stuff, references to him in other people’s writing and so on. Certainly there’s enough to build up a broad-brush picture of his life. What there isn’t is much that is truly personal: no letters back and forth between London and Stratford, no learned essays on theatrical technique, no gossipy personal journal.
So instead of the common pattern of literary biographies, where the biographer tries to use the details of the life to shed light on the work, here it’s more often the other way round: trying to mine the plays and poems for details that might tell us something about his life. It’s all hints and scraps, and any conclusions are tentative and contingent, but it’s all quite interesting even so.
In the end, I think Shakespeare remains elusive: but then, if we knew every moment of his life, I suspect it would only serve to emphasise the fundamental mysteriousness of genius. What biographical detail could possibly be adequate as an explanation?