Enemies and Allies is excellent. My favorite thing from Kevin J. Anderson and since I don't like his work much that's saying a lot. The Last Days of Krypton is bad, but some have liked it here.
What characters other than Batman, Superman, and Lex Luthor are in it?
I came across Enemies and Allies
at the library and remembered the recommendation here, so I picked it up. It's got Clark/Superman, Lois, Perry, Jimmy, and Lex on the Metropolis side and Bruce/Batman and Alfred on the Gotham side, with a brief appearance by Captain James Gordon and cameos by a couple of society figures named Kyle and Cobblepot. It's also got President Eisenhower, Joseph McCarthy, and Eleanor Roosevelt.
It's an okay book, an interesting alternate history of Superman and Batman, but there are some failures of research both in history and physics, things that most readers probably wouldn't be troubled by but which stood out for me. And it was a bit odd seeing a story set in 1957-8 but featuring more modern versions of Superman, Batman, and Luthor.