I went to the concert premiere in Chicago in May, and I'd say it was entirely worth it.
Nobuo Uematsu, Koji Kondo, Yuzo Koshiro, Takenobu Mitsuyoshi (Shenmue, many other Sega games.. including Daytona USA. Yes, he did the singing.), Akira Yamaoka, Jason Hayes, and Joel Eriksson attended the one I went to, were there any special guests/ performances at the other concerts?
Koji Kondo got on stage and played a piano solo version of the main tune from New Super Mario Bros, and Akira Yamaoka went up to play the lead guitar and just rocked out on Laura's Theme from Silent Hill 2.
Angela Aki came up to sing Eyes on Me and Kiss Me Goodbye, also.
What special things happened at the other concerts? I know certain stops had different things, I'd love to find out what happened!