In a nutshell, I'm extremely glad I bought this book. Many considered The Ultimate Avengers an attempt by Dave Rogers merely to sell another book. They mistakenly believed that it offered very little new information than his previous Avengers bible, The Complete Avengers, thus rendering Ultimate rare and hard to find. It wasn't even released here in the States, making it even harder to find at a reasonable price. You have to look on Amazon UK to find USED copies at reasonable prices. (New copies are almost impossible to find.) Even then, buying this book from the States using American funds will cost you more than double the listed Sterling Pound price due to the exchange rate.
There is enough new information in Ultimate to warrant owning both books. While much of the text in the season by season overview is a straight word-for-word reprint or paraphrasing of Complete, there is plenty of new info in these chapters, much of it Rogers had sent to him from Brian Clemens, himself. Some of this new info corrects factual errors that creeped in Complete. For example, Rhonda Parker "was not a happy accident" -- as was claimed in the previous book -- "she was planned and written in the scripts from day one". This excerpt is from Clemens' notes to Rogers, as appear on The Ultimate Avengers, page 14.
Additional new features in Ultimate include sidebar notes consisting of background information into the production of The Avengers. Rogers arranges these notes in episode form throughout the book, appearing close to the synopsis of that particular episode. Not all episodes are represented with these sidebar notes, but most are. The episode synopses represent another difference in the two books. Gone are the lengthy, page-long detailed descriptions, to be replace by a very brief paragraph offering a general plot description of each episode.
Aside from a totally different set of photos, Ultimate sports an eight-page color photo insert featuring some beautiful glossy pictures, including the infamous shot of Cathy Gale in a black bra, sitting on her bed, from The Man With Two Shadows, which likely caused such a stir back in the early 60s. Also, Ultimate offers reprints of scripts not seen in Complete, such as an exact reprint of the script for "The Strange Case of The Missing Corpse", a short skit to introduce the series to an American audience, as well as a written description of the opening title to season five, the first color season.
All the above-mentioned new attractions, along with an updated merchandise guide, make The Ultimate Avengers well worth owning. I gave The Complete Avengers five stars in a previous review, a justified rating. However, I wish I can go one up in my rating of The Ultimate Avengers, but alas, Amazon's rating system only goes to five stars. So consider this an unofficial rating of six stars, even though only five stars appear. After all, The Ultimate Avengers very well lives up to its name, a slight improvement over The Complete Avengers.