Let me start by saying that I generally love Paizo products and have bought more than my fair share. The quality of their work is generally very high but I had a number of problems with the latest book. This has less to do with the content of the book and more its presentation. I have the original AP and I love both the old and updated content I've read so far. Now about the design ...
1) The paper texture imagery used on the pages of the book is too strong, particularly at the bottom of the page. At the top it might be reasonably light, but the legibility is pretty poor at the bottom. It can definitely still be read, but I'm very conscious that I'm trying to read something, which should not be the case.
2) The images used of the old covers in the upper right corners are too small to be useful for much and interact poorly with the rest of the design. Designing an icon or some other representation would work better (similar to the head shots on the left page). What is the point of the small type from the original cover if it can't be read? It really feels like wasted space which isn't a huge deal but it tends to draw the eye to it because it is often the only white highlight on a mid value page.
3) The way the text that is to be read to PCs is stylized works poorly with the rest of the book design. The black gradient bar combined with a grey back ground, combined with grey type makes it all look like mush. As far as I can tell gradient bars aren't used anywhere else in the design making them appear out of place with everything else.
4) Much further down on big issues is all the outlined type used. The cover art is great but does every piece of type require an outline? The pathfinder logo looks fine, and Rise of the Runelords is OK but outlining Anniversary Edition is taking it a little too far and it also becomes illegible.
After panning the above let me mention some things I did like. Generally the maps look great and the keys are clear ... some might be surprised that this is not an easy thing to do.
I also like the information design of the call outs on the edge of the page, breaking down the chapters. But theses are also very hard to read because of the paper texture under them and the vertical "edge" that passes through them.
The design of the left hand page of the spread is very nice, right side would have been much better if it had taken that style then modified it with the different information. The slices of images and PC headshot looked very nice.
I couldn't decide between 3 and 4 starts, but since the content was great, I decided it pulled the overall score up. I debated writing this review at all, but I decided if I didn't mention these things then how would Paizo know what to keep an eye on next time.
Thanks for the great products.
edit: after more time it doesn't get better ...
The chapter breaks are much worse than previous books. There is no clear hierarchy, and using a white glow to make something standout from a cluttered background is a design student crutch. Professional designers should know better.
The new headers bring more attention to themselves then the cogent inside them. The same Art Director and Graphic Designer are listed for this book as others, but it is very much a step backwards in design. If this is the new style going forward I hope Paizo will reconsider. The older books where much better.