It's very much a middle installment, there's a good amount of action but it spends most if its time developing the characters, the relations between them and the final confrontation to come, as well as a further focus on the ecological state of the earth in the early U.C. 100's and how it is weaponized by the Earth Federation elites.
Gigi is the biggest benefactor from the extra time spent on the character, clarifying her activities as well as a dwelving more into her personality.
Also Tomino really want you to know that it's hot aboard Mafty's vessels, everyone sweats so much.