More like a 3-4/10, and not as a comparison to the original, but as a standalone. This is especially true because I don't know how anyone who hasn't seen/read the source material could understand what even went on, much less enjoy or care about it. Most moments were so rushed, that a lot of what was conveyed in the original was missing. Moments of humor were shallow, characters felt bland as shit, and attempts at setting atmosphere fell short (bgm,establishing shots, sound effects, etc.). Not even in comparison to the original, in general everything was just shallow. I'd gripe about changes they've made to characters, but the pacing was so ADHD, I could hardly even discern what they did to the characters; they did a really poor job at character building. Pretty much all that went down was a constant loop of one 3-5 second haha sequence followed by another. This wouldn't be so bad if there was any appealing satire, like in the original, but they took out practically every bit of satire/dark humor, or dumbed it down.
For example, they undermined the "I wish I never had you" joke so that it came out less harsh. It's so moefied I can't imagine ever giving a shit about any of the new characters, nor enjoying the humor, even if they could do anything more than emote a face or push a joke in their 3-5 seconds of time before the next characters' turn. At least when the original became a 5 second joke sequence spammer, it still had the satire, atmosphere (especially bgm), and animation to go with it.
About the animation, god damn can it be hard to look at. 70% of the time it's sparkly eye rape, and when it isn't, it's generic digital backgrounds. Although you said the backgrounds are a pro, I doubt you payed more than a glance to them, although I don't blame you, since one reason for the ADHD pacing is probably to hide the backgrounds. Pic related shows a couple new backgrounds and an old one. I won't gripe about the characters not contrasting well with the backgrounds because that's pretty much standard. However, you can clearly see the bad contrast of different aspects of the background that were put together for the final thing. For example, in pic related, basically all the uncanny valley, digital bushes, houses, telephone poles, and other infrastructure contrast horribly with the whole thing. But besides that I'd say everything else was good enough; character movements were fine, faces were alright, and there wasn't really much else that stood out as especially low quality. Again though, putting it all together, it was shallow and nothing above a 4/10.