I just finished it, would say it's like 7.5-8 imo. All the good parts come from Frieren herself. Her autism, her hatred of demons, and the kindergarten-level existentialism philosophy coming from her learning to cope with short human lives.
And the overall mood of the comfy adventure, but for some reason I wasn't feeling it that much the further it went. Probably because a lot of the episodes felt almost like a blatant fillers except they all are connected to the story every time, but sometimes it still feels like a a filler, and some of them were comfier than the other. I can't even pinpoint a single episode that is plain good or bad, it's more like each episode has great or bad moments here and there, but it never feels like there's enough of those great pieces.
Almost all characters are boring cardboards, even Fern and Stark who are main characters could've used some actual development. Also holy shit Fern is even more autistic than a 1000 years old elf who raised her, except not in a good way.
I really really liked the TDD way Frieren deals with demons and I wish there was more of it. All the other combat, it was okay, generic anime shounen battle. Last FvF fight was cool, even if mostly just carried by the really flashy explosions.
The soundtrack was surprisingly mediocre.