Fire Garden is an amazing recording to say the least It rivals the album Passion and Warfare. The musicianship,composition, and production is of an extreamly high quality.
The album opens with an insane song titled "There's a Fire In the House" then lightens up a bit with "The Crying Machine" Phase 1 is insturmental and is ended with the " Fire Garden Suite" and it's four movements all very indian like. The first one is guitar the second is a sitar, the third piano and acoustic guitar duet, the fourth is heavy with grooves not used much in western music and searing leads.
Phase 2 has lyrics with heavy influence from Frank Zappa in terms of composition not so much in lyrics.
You can't compare vai with anyone because he is himself no matter what he's playing or writting it's always his personality showing through but he is virtuoso by all means.