I agree with most of what was said below as far as the sometimes shoddy cut and paste job done and missing things like the agile weapon.
It seems to me, with the time they had to put this together, there could have been more attention given to the accuracy of the information (i.e.: incorporating all errata that may have been published since the original publication of an item) as well as spelling and grammar.
That aside, it is still a very useful volume to have. I do plan on getting this in PDF as well, but I may wait a year or so to see if they make some corrections first.
It's obvious that Paizo not only has a strong passion for the 3.5 rules set but also an intimate knowledge of its mechanics. The changes in the classes are very well done, and amazingly well ballanced. The chnges made in the rules (especially the CMB/CMD mechanic) not only streamline the system but also makes those rules more versitile.
The book is also well laid out and graphically beautiful.
Anyone who is not interested in the new 4E rules should seriously give this a look! You will not be disapointed, I garuantee it!
