Depends on what type of story you think it's telling. I'm at a disadvantage in that I didn't actually finish Fourze (got to about the same place we're at with Wizard now) so I can't concretely say where they went at the end, but from the opening episodes and the ones I saw afterwards, I'm thinking it was a story about friendship.
Friendship is certainly one of the themes of the show, but it's not the only one. I think instead the show views friendship as, essentially, the way to resolve the various conflicts it's exploring. The central conflict of the story is the generational divide, and how teenagers find themselves in a strange place where they're supposed to be on the cusp of adulthood, but still find themselves at the mercy of adult whims, which can be very selfish.
To an extent, all of the narrative hinges on the difference in worldview between Gentaro, who places friendship above all things, and Gamou, who was willing to murder his best friend in order to achieve his life's ambition. Friendship in Fourze is an absolute good, though it does not always solve problems successfully. That said, someone who respects the idea of friendship generally comes out ahead of someone who doesn't.
A significant problem with Fourze is that even though the story is really about the clash between Gentaro and Gamou's worldviews, all of the direct confrontations between those two characters are hopelessly rear-loaded. We don't even have a clear idea of what makes Gamou tick until the last four episodes. While Fourze is probably the best possible version of the story it wanted to tell, the
pacing of that story is very easy to call into question.
Really? What about Fourze's story concept necessitated things like drills on legs. Or, worse--using said drill for anything other than a finisher?
The Fourze suit was explicitly made for the purpose of letting humans (specifically Kengo) travel through space to meet the Presenters. Rokuro's intention was clearly that it be mass-produced at some distant point in the future, probably long after his death. It was created for exploration purposes, so in theory a lot of its goofier modules play into that idea. The drill was probably intended to help crack apart asteroids and other forms of space debris that might prove dangerous during the voyage to the Presenters. It could perhaps give the descendants of the original Fourze suit some potential as mining technology.
(That said, the actual
actual reason is clearly that Kazuki Nakahsima loves the hell out of drills, which aren't just the main weapon of choice in Gurren-Lagann but a central metaphor in the series. I wonder if the original impetus of this idea was 1997's Megaranger, which has a very similar tone and premise to Fourze (though a very different story). In Megaranger, the Red's weapon is a drill saber. Parts of both Fourze and Gurren-Lagann give the impression that Megaranger made a
huge impression on Nakashima at some point. Certainly, some of Fourze's modules are extremely similar to pieces of Megaranger gear.)
It may be bad, but it at least tries new things, like with White Wizard, Mayu, etc. Do we all like these? Evidently not.
I think it's more that the show hasn't
done anything with these elements yet, so it's hard for a hostile or neutral audience to form any particular opinion of them. We don't know, strictly speaking, if we'll ever see Mayu again at all, let alone if her fate will be anything that's memorable. The show hasn't really said anything about White Wizard other than that he exists, and we don't know what his motivations are. To an extent, we don't know what Mayu or White Wizard's overall role in the story will be yet. In that situation, it's hard to count the characters as net positives, because there's just not a lot of substance to either yet.
The show really missed the opportunity to run with the idea of a hero's actions ultimately being beneficial to the baddies.
I imagine this stems from another fundamental problem of Fourze, which is that it was perhaps overly-similar to Kamen Rider W in many respects. In W, it is also a major plot point that W's actions ultimately serve Ryubei's interests, by unlocking the Xtreme powers. There is a major scene where Ryubei really plays this up, and in that show, it's a big shocker that helps explain why Ryubei never fussed about stopping W the way that subordinates like Saeko and Kirihiko did.
They clearly didn't want to duplicate that scene in Fourze, so there's never a point where anyone points out that Fourze's battles are ultimately to Gamou's benefit. The lesser Horoscopes (sans Virgo) clearly think of Fourze as an actual threat, and treat him as such. By the end of the show, though, it's clear that the only Horoscopes who really understood what Gamou intended from the start were Leo, Virgo, and Libra, so the other Horoscopes were basically just being idiots.
That said, we see the lesser Horoscopes way earlier in the series, and there's never a scene early on that explicitly points out that their attitude toward Fourze might be completely unrelated to Gamou's. In short, it's easy to form the wrong impression of the Zodiarts, and you'll never have a chance to realize it's wrong unless you finish the series. Which, almost by definition, most people won't. This goes back to the problem of too much of Fourze's narrative being rear-loaded.
