As someone who just started getting deep into Gundam over the last ~6 months in anticipation of GQuuuuuuX, I have to say that it doesn't come as much of a surprise that I really loved it.
I've been a big fan of Gainax, Khara, Anno, Tsurumaki and Enokido for roughly 25 years now, and I feel that GQuuuuuuX pulled the rabbit out of the hat by bridging old and new. I feel that they hit the 7-10 split of making a show that was simultaneously respectful and fanboyish about the original Mobile Suit Gundam, while still managing to fight against it both literally and symbolically. Would it be a good show to watch for someone with a "death to the author" attitude who wants a purely stand-alone story? Maybe not. But I don't think that's what GQuuuuuuX was attempting to be.
Say what you will about GQuuuuuuX, but it was absolutely a love letter to 0079, Zeta, CCA, the entire UC timeline, and most importantly, the people who made it--who, had they not existed, Gainax, Gunbuster, Evangleion, FLCL, Diebuster, Khara also would not have existed. Maybe I'm just being sentimental, but I felt that GQuuuuuuX was a statement about life and circumstances. It was a show about all of the other possibilities that could happen in life if things were just a little bit different. And it was a show about how people like Tsurumaki built their life and career on the shoulders of people like Tomino, who in turn also benefited from being the right person, at the right place and time, especially compared to the wartime generation of Japanese people who came just before him.
As such, I think GQuuuuuuX is best enjoyed with knowledge of the UC and an appreciation for the meta-narrative.
I didn't go into this show (or The Beginning movie cut, which I saw in theaters twice) expecting it to be totally divorced from everything that came before it. From the first minute of seeing GQuuuuuX The Beginning, I was sold on the idea of this alternate-UC, a version of the Gundam UC universe where Amuro doesn't get in the robot. This show was answering that specific question, "what would Gundam be like if Amuro never got in the robot in the first place?" That was what set the stage for the entire continuity that Machu and Nyan existed in, and I also think they did a good job of exploring not only why such a universe might exist, but also what that would mean for other characters in the UC framework, and even the design language of the mobile suits!
I've seen people complain that GQuuuuuuX is either too heavily reliant on UC or that they would have preferred more focus on the UC characters. But what those people fail to understand is that GQuuuuuuX is UC, and so characters like Char, Challia, and Kycilia are just as much native characters to the GQ-UC timeline as Machu and Nyan are. They are not actually even really the same characters as their 79-UC counterparts.
One thing I want to say about the show is how much it evoked FLCL, including the ending:
GQuuuuuuX and FLCL SPOILERS
In FLCL, the young and disillusioned male lead Naota's life is suddenly and radically changed when the mysterious weirdo girl Haruko crashes into his boring, normal life. By the end of the story we find out that Haruko is in fact an alien who is chasing after an all powerful amorphous entity called Atomsk whose power/essence has been captured by Medical Mechanica, a mysterious organization that is trying to achieve something along the lines of the Third Impact from Evangleion. In the end of the story Naota finally steps up and takes agency over his life, stealing the power of Atomsk from both Medical Mechanica and Haruko, before suddenly backing off to confess his love to Haruko before Atomsk escapes and Haruko, having failed to do what she came to do in the first place, follows. From there, life goes on.
In GQuuuuuuX, it is eventually revealed that this strange stoner kid Shuji is far from a normal newtype, but is actually some kind of strange being from another universe. Is he a real person, or some kind of manifestation of Lalah or the Gundam? (Just like Haruko, we never really learn the full truth.) Shuji exists in the GQuuuuuuX universe for a specific reason, to destroy the universe itself in an attempt to help the mystical newtype Lalah search for a version of the universe where the love of her life, Char, is not killed trying to protect her. (I definitely have to rewatch it to wrap my mind around this, but I think that's the basic idea.) Machu and Nyan, motivated by existential freedom and a desire to do whatever needs to be done to survive and get by in like, respectively, find themselves in the middle of this battle across universes that is much bigger than themselves, and Machu eventually takes agency over her situation when she shoots the limiter drive within GQuuuuuuX. Much like Naota, Machu both foils Shuji's plan and confesses her repressed feelings towards him before he disappears. Machu's life, also, goes on.
I think people have some legitimate complaints about the break-neck pace of GQuuuuuuX. Tsurumaki is no stranger to telling fast stories over a small number of episodes, but it could be argued that GQuuuuuuX had so much to say in its allotted time that it wasn't able to have as many of the moody and atmospheric moments as shows like Evangelion, FLCL and Diebuster have. (FLCL is famous for being frenetic, but it also has some truly beautiful calm scenes!) We got a bit of that in GQuuuuuuX, like Nyan's montage in Episode 5, but if the show had a little bit more time maybe we could have spent a bit more quality quiet time with our main characters, especially Machu and Nyan. (On the other hand, people wanted more FLCL, only for the monkey paw to curl with the creation of 4 subpar spinoff cartoon network cashgrabs... Sometimes less is more!)
Overall, I really loved GQuuuuuX.
I spent the last few months really looking forward to every release, watching it multiple times and looking at a lot of the online discussions around it. I haven't been this excited for, or had this much fun watching a new anime in many, many years. I'm sad that it's over, but very glad that it was created. As someone who only watched 0079, Z, ZZ, CCA, 0080, 08th MS, Unicorn and WfM this year (with a couple episodes of Wing back in the Toonami days), I can only imagine how a show like this would feel to people who watched all of this stuff when it came out. If nothing else, it was a new Tsurumaki + Enokido show by Khara, with participation by Anno, and an absolute love letter to Mobile Suit Gundam.
The overall aesthetic of this show is so, so perfect. That was a fantastic trailer too.