Being rather new to the Avengers had this volume of Avengers Assemble leaving me scratching my head. This volume is definitely for folks who know the Avengers and have known the Avengers for years and years and years. Overall the story wasn't bad, but having just read Avengers Assemble volume 2 and the Ultron story within, this volume is just a quagmire of history.
Perhaps I would feel different if I knew the old characters and understood their significance. But, considering I have enjoyed both the first and second volumes of Avengers Assemble, knowing as little as I do about them, my only guess is that this volume relies more on the readers knowledge of the past. I constantly felt like the scenes I was witnessing should be more dramatic, should have more significance if I just understood the complex relationship of these villains to the characters. I know Perez/Busiek is a great team, but Perez actually leaves the series during this volume, which is somewhat of a sad turn for the series.
It has some highlights, some "evidently" dramatic turns, but overall, not nearly as good as the previous volume. If you are a long time fan, this book is for you. If you are a newbie, or just want to collect the best, then avoid this volume.