Reaction has been, to say the least, mixed. For example, The Grauniad tries valiantly to read it straight, concluding that
[A]rmy historians fault military and political leaders for focusing excessively on toppling Saddam Hussein in 2003 without looking towards a broader transition towards a stable society. Actions by the former defence secretary Donald Rumsfeld and the top US commander during the Iraq invasion, Tommy Franks, are singled out in the study, which was delayed for six months to allow senior army figures to review drafts.
but not once citing the Pentagon Papers, or Ellsberg. It's been four years now since a piece in the San Francisco Chronicle interviewed Ellsberg himself, who predicted that something like this book would eventually find its way to the public (although the GPO still, at this writing, shows release as "frozen", so you may need to go and download your own copy (PDF, 103mb(!!))).
The saddest aspect of On Point II, though, is that its conclusions were predictable. Indeed, a significant level of detail was inferrable by people with a few brain cells to rub together — let alone people with actual knowledge of Southwest Asia — just from the public rhetoric of George III and his psychophants in the months between 9/11 and the actual invasion of Iraq. And this is sadder than the actual losses in Iraq, which I do not minimize, because it is yet another example of preparing to fight the last war... and choosing, as one's "last war" model, one that we lost.