I've read critical comments on-line related to the accuracy of some of the sections.
Some of the criticisms seem a bit over-zealous, particularly as the Oxford Companion covers a great deal of territory, but nonetheless you'd like it to be accurate.
Most of the criticisms I've seen can be found at the Shut Up About Barclay Perkins blog.
If one is presenting information as
history, I don't think one
can be over-zealous. As such, it seems to me that most of the criticisms of the OCB tend to be pretty well founded. I certainly like the concept of the book and commend the massive effort that went into bringing it to print; but by the same token I don't think it's unreasonable at all to expect a book bearing the Oxford brand name to be a bit more careful regarding what it presents as 'fact'.
In any case, I'm supposing that there will surely be corrections/amendments when another edition rolls out...at least I would hope so, given how they've been 'called out' on some of the info, not to mention how the landscape of brewing itself is still changing.
Meantime, there's this helpful and useful work-in-progress (link below) that addesses some of the more glaring inaccuracies and which, down the line, will hopefully help to simplify the job of making the second edition more accurate.
As it stands now, the wiki referenced below takes the high road and serves to help in the correction of the more glaring errors, rather than creating more controversey. And, I think it serves as a very good companion to
the Companion:
http://ocbeercommentary.wikispaces.com/