This is a well written book that covers super powers in great depth. It does have problems relating to other point based systems in GURPS such as racial abilities, normal advantages, and so forth. In addition, you can forget about creating characters like the Green Lantern or Quicksilver... those abilities just are not in the game.
The sample setting is a lot of fun, an alternate Earth where super-powers reign and super-teams support the benevolence of a powerful United Nations. Unfortunately, it is marred by characters that delve into thoughtless or even insulting stereotypes: Flamin' Jane (hot, lecherous lawyer with red hair), Black Pearl (Aquaman, only black and female), Pouka (Scottish), Argurous Astraph (Greek who throws thunderbolts), Mount Fuji (you get the idea), a Russian who is depressed and alcoholic, a dwarf with dwarf star powers, Rebel Yell (Southern bigot), and so forth. Whether a deliberate homage to tasteless 70s style exploitation and gag characters, or simply stereotyping gone awry, I just cannot fathom how these characters saw print in this form.