Whereas Titan was a very good explore the big space object novel as good as or better than Ringworld or Rendezvous with Rama, Wizard improves with some new characters and fleshes out Cirroco and Gaby from Titan.
Gaea, the living entity/world has now established an embassy on Earth and allows immigration/visitors a few generations after Titan. Supplicants in need of something from Gaea such as a disease cured are allowed to come to Gaea and she amuses herself by making them perform "heroic" feats to get the boon they wish.
We are introduced to two characters from Earth, a youngish girl from a space colony of lesbians suffering from a type of epilipsy, and a fellow with what seems to be multiple personality disorder. After reaching Gaea they join up with Cirroco and Gaby and the story really takes off.
All of the sense of wonder of exploration from Titan is still evidenced here, and is even more imaginative. However the characters struggling with their issues as well as the environment is what drives the story and makes you care what happens. Cirroco has become a functional alchoholic, Gaby remains the most normal but bears the scars of loving Cirroco.
Visiting the regional brains of Gaea allows the two visitors from Earth to develop their character while showing us more of the wonders of Gaea. Eventually we learn the visit is to sound out the possibility of a rebellion and the dramatic tension heightens.
Though the book provides full closure to the story, there is a definite hook to Demon which will make you want to move right on.
This is a fast-paced, fun read that is more than worth your while. I cannot believe I have waited this long to experience this bravura performance.