Why is gyaru yuri so goooood
I think - and this is totally my two cents here - it's because gyaru is inherently about self-expression; an intentional counter to Japanese culture of demure stoicism. So, with that in mind, you know that when a gyaru does or says something, she means it whole-heartedly; there are no filters. It is the honest truth because, if it wasn't, it wouldn't be gyaru.
This is why "gyaru + X" relationships are always fun - such as in Citrus - because there's always going to be a driving force towards something; it may be clumsy and silly and difficult and even completely inconsequential, but there are no antagonists needed to drive the plot: the gyaru is already at the wheel.
Pairing two gyaru up as we see here is, to me, like a breath of fresh air. How often do you see the story where two people are in a will-they-won't-they relationship that is constantly hampered by a lack of communication? If those two idiots would just open their gab-holes and TALK TO EACH OTHER they could skip 30 chapters straight to their happily-ever-after. In '#Gal and Gal Yuri', it feels like... that's what we did: we skipped right to the end, and we get to see two people in love gushing over each other, and basking in the honest, honey-sweet feelings they have for each other.
Yes, it's nice to have character growth and dynamic narratives and action and tension that rises and falls... a slice-of-life fluffy cute-fest may not be "interesting" in the classical sense. But if you do it right, you can avoid the sickly-sweet over-saturation and instead create a heartwarming indulgence.
And maybe there will be tension to come; maybe this story will take the well-trodden path of "oh no, they're not going to the same college together" or "oh no, they're entering Japanese society and now they have to dedicate the rest of their lives to a company rather than to each other". I wouldn't be surprised if it does, but I would be disappointed; I'd like to see a win for the gyaru movement. I'd like to see them make it work on their terms, to find both happiness and success without abandoning their non-conformity.