This is an Order of the Stick book, but not in standard continuity. The heart of it is the 22 strips that he did for Dragon magazine, which had little internal continuity, owing to the new reader problem -- except for the last three, which are a lament on the magazine's death. (One appears in the original form for the first time; the Wizards of the Coast disapproved of it.)
So, he added more filler. A Julio Scoundrel tale. Some bonus strips for the Dragon ones -- and a segue into a tale where they meet up with their 4th edition counterparts. (His most requested story line. After all, the first Order of the Stick comic was about characters undergoing a transformation to 3.5.) And when they trade stories, they are amusing in both what they choose to fracture beyond recognition and how they do it.
Lots of humor. Plus Burlew's accounts of writing stuff.