I think it will be hard for any super-hero fan to read this book without a big smile crossing their face. Although Busiek sticks with the sort of cosmic Infinity Gauntlet/Crisis on Infinite Earths style that has defined this book, this issue also has a lot more of the smaller moments (and smaller characters) that fans love. The story is deliberately confusing, as not even the heroes know what is going on, but it all makes a sort of sense by the end, and although the feel is reminiscent of the merged universe of Amalgam that came out of a previous DC/Marvel crossover, this one feels slightly more pure from a straight super-hero point-of-view. In addition, Perez's work here is stunning, with a little bit less of the overcrowded panel feel that weakened the second issue while maintaining the same insanely detail-oriented style that has made him a favorite in this field.
I'm pretty sure that everyone reading JLA/Avengers came into this with some sort of favorite moment they were hoping to see. The Thor/Superman smackdown. The Batman/Captain America team-up. For me, the thing I wanted to see, and was afraid we might not get, is interaction between the two similarly stubborn and outspoken bowmen of the DC and Marvel universes. Happily, Busiek and Perez provide several moments in this issue where we get to see exactly the sort of fun rivalry and argumentative relationship that I was hoping for, and that small thing, if nothing else, would leave me pretty happy with the series as a whole.
Of course, that's not the full extent of what made this issue so much fun. Busiek's story is very much in the tradition of previous cosmic stories and crossover tales, focusing on super-heroic scavenger hunts and powerful high-level villains, and this issue is very much in that kind of tradition too. What's really cool, though, is that he takes several traditions and sort of smooshes them together to make a very entertaining whole that seems fresh and fun despite the familiarity of the structure. The worlds have collided, and continuity is not as it should be, and so we get unusual inter-dimensional team-ups and stories that might have existed had the DC and Marvel universes been linked since the beginning. It's exactly the sort of playful fun that should happen in this kind of crossover, and no fan of either universe should leave this issue disappointed, because Busiek and Perez are clearly having a lot of fun mixing the different toys in different playgrounds.
What's really fun about this non-continuity approach is that Busiek gets to do a lot of fanboy wish-fulfilment. Because the continuity is out of whack, he can play with the original Flash and Green Lantern if he wants to instead of their newer replacements. He can use whatever Avengers strike his fancy instead of the current line-up. He can even use characters who have been dead or radically changed as if they never had been, allowing him to do one-off moments (like Snapper Carr and Rick Jones collaborating on a cheeseburger) that would be a waste of space if he had to set up how these characters all fit together in a more structured way. The shifting time is a plot point, but it's also a bit of a cheat, a welcome one that allows Busiek and Perez to mix and match on a whim.
This is one of those projects where it's hard to imagine anyone else doing it. On the writing side, there are maybe two or three other names that might have pulled it off, but Busiek is so perfect for the role it's hard to imagine them doing it at this point. On the art side, though, it's really difficult to imagine this project working without George Perez. Even with the oversized issues, there are so many fun moments to work in that even the best writer couldn't manage it alone. Perez's tendency toward completely insane group scenes and backgrounds fills the book with "Easter eggs," little in-jokes or scenes that take place entirely in the art but which set the tone of the book as much as the script does.
However, just because this issue contains more fun fannish moments than the previous issues, that doesn't mean that the plot has been left abandoned by the roadside. JLA/Avengers really is all about fun, a reward of sorts for long-time super-hero readers, but Busiek has not forgotten to include the dramatic underpinnings that make it all matter. There's a fantastic scene later on in the book where the heroes are confronted with a difficult choice, with all their mistakes, and they choose to do the heroic thing rather than the easy thing because they know it's right. It is the epitome of super-heroic morality, and it's as important to the integrity of JLA/Avengers as the more fun elements like seeing Superman and Iron Man in the same story.
