I think that the Giant Form spells need to be lowered by one level. Right now, Giant Form II and Form of the Dragon III are both 8th level and both allow you to assume Huge forms. However, the Huge dragon form can fly and breathe fire every 1d4 rounds. Surely the Huge giant isn't as powerful as that?
Oh, and can I just add that the new polymorph spells are MUCH better than the old 3.5 version. In 3.5, a 8th-level wizard can polymorph into a digester and squirt 20-foot cones of 4d8 (Ex) acid damage at enemies every 1d4 rounds for EIGHT MINUTES with a 4th-level spell. That's insane.
Oh, and can I just add that the new polymorph spells are MUCH better than the old 3.5 version. In 3.5, a 8th-level wizard can polymorph into a digester and squirt 20-foot cones of 4d8 (Ex) acid damage at enemies every 1d4 rounds for EIGHT MINUTES with a 4th-level spell. That's insane.
In Pathfinder, an 11th level wizard can Beast Shape IV into a gorgon and use a petrifying breath weapon 5 times (DC = spell DC). That's still insane.
One comment about Giant Form -- you should note that your equipment doesn't meld into your body when using it. That's one reason you might want to use the spell. I agree that the level is probably too high, though.