This anime is, at its core, a love letter to VOCALOID and the culture surrounding it. If that's not your cup of tea, that's fully understandable!
And I definitely think it would detract from how much someone enjoys this anime, but I do however think that this is not a bad anime. And I also do think there are things to enjoy even if you don't like VOCALOID.
Let me explain.
The anime follows a boy, Saku, who lives in a city surrounded by a big white wall. No, really. It's bizarre.
In this city, he lives a normal life - goes to high school, has a deathly sick sister; you know, the usual stuff. His sister's health is declining rapidly, so rapidly that he refuses to join a song trio with the deutergonists, Uta and Sosuke. In his desperation to save his sister, he remembers her telling him that the "white shadows" (beings that co-exist with them in the world) can grant wishes and, by some stroke of luck, him singing Uta/Sosuke's songs gathers a crowd of these white shadows.
As you can see, it's a pretty standard plot for your typical idol anime, but... white walls?? White shadows?? What???
Well... that's the charm of Actors! The story is absolutely bonkers. There is definitely no point in the story where you'll be able to predict what's gonna happen next, and I do think that's the beauty of it.
It's quirky on purpose, definitely a love letter to other surprisingly dark slice of life anime like Kemono Friends, so the story was entertaining to me.
As for the VOCALOID part of it...
Each episode has a cover song of a VOCALOID song sung by the characters. Why is that? Well, Actors is (was?) a CD cover series where-in famous Japanese voice actors sing VOCALOID songs. Although this exists in plenty by now, especially with the popularity of games like Project Sekai, back when Actors came out, it was pretty much the only thing of its genre.
First and foremost, the anime is a project made for the loyal fans who stuck by the CDs for 10 years (!!), just listening to song covers and hearding drama CDs.
If you're confused by characters, don't understand why they're sometimes shoehorned in/underdeveloped, et cetera, that is sadly just the reality of these anime adaptations made for fans. I didn't mind this as I've been a fan for a long time, but it is definitely a detract to most people coming blind in. Hopefully the anime sparked your interest in listening to the CDs as well!
Overall, I think this anime adds more than it detracts. Is it a masterpiece? Absolutely not. Far from it. But I think the insane premise, the music and the ability to turn off your brain and just enjoy it as an "cute boys doing cute things" anime makes it a net-positive overall.
