The technical sequel of Gunbuster!!!!!! but the spiritual sequel of FLCL....
Anyway, wile Gunbuster was more of a depressing story, this one is more uplifting and "badass." I would say that it was a prequel to Gurren Lagann in ways such as style and philosophy (I mean just look at Nono).
Over all, this was a more fun show to watch compared to gunbuster and its art was definitely prettier. Also, the director of this show is about 50 million times superior to Anno, as Anno cannot direct his way out of a paper bag.