Where Guggenheim really gets it right is in the first chapter: recapping the JSA's history and influence. He's aided in this chapter by stellar art from George Perez and decent art by Freddie Williams II and Howard Chaykin (Chaykin, in particular, is capable of so much better). It's clear Guggenheim understands what most long-term fans of the JSA love about the team.
The dialogue in some sections is really crisp and snappy, especially between the JSA and Challengers of the Unknown. I actually would like to see what Guggenheim would have done with the classic Challengers after seeing how he wrote them in this installment.In other places, the dialogue suffers from having to cover in exposition what I assume the writer would have covered with action if he'd been given more issues to work with.
I'm of two minds about the revamp of Per Degaton. On the one hand, it's always nice to see a second-tier villain given a shot at becoming something more; on the other hand, I sort of have always loved Degaton as the loser of time-travel villains.
Overall, I liked this installment better than the previous.