On the positive side, he sheds new light (for me) on the action of USA in the Near and Middle East.
On the negative side, there are a lot of pages on September 11 and in particular that GW Bush and Dick Cheney have done that day. It's full of details that do not add much except that some versions are contradictory.
It is clear that the author is close to a semi-complotiste version of the September 11 attacks. It is not a priori a negative point but it is not defended very well, I think.
In short, very interesting information but also many details not to move forward.