Most of the criticisms leved against it relate to the identity of Monarch being changed last minute. I've never read the crossover the whole way through, but what I have read has been stellar.
Amarageddon 2001 Special 1 I felt was not just a great superhero story, but a great dystopian narrative and time travel story as well.
Justice League America Annual 5 is probably the best tie in issue for a comic I have ever read. It's a perfect swan song for the Justice League International team.