I mean it's not particularly bad, it's just not very good either.
So what I'm saying is you might enjoy this if you like cute-girls-doing-cute-things / moe-blob shows.

Story: 4/10
Unaging girl has been getting ~50 exp every day for the past 300 years, so now she's max level and very powerful, but she doesn't care, all she wants to do is laze around peacefully. We've had more or less 3 arc now and all of them have gone more or less like this:
> Knock knock on the door.
> A X shows, lighty bothering Main-character-chan and demonstrating/announcing a problem to come.
> Some time passes.
> Problem to come shows up and challenges mc to a battle.
> Problem to come fails by herself (spoiler alert: no guys).
> Turns out she's not a bad girl.
> Pass time and repeat.
At least this fits the theme.

Art: 5/10
It's a somewhat-round-bubbly artstyle. Like slightly bubbly, but not enough to be particularly worth noting. But i am noting it here because there really isn't anything worth noting about it. It's nor good, nor bad. It's nor interesting, nor boring. It's nor detailed, nor minimalist. I could go on for a long time about what the artstyle isn't so i'm gonna stop.
At least this fits the theme.

Characters: 3/10
The lack of originality / interesting things hits the characters more than any other aspect of the manga. The main character is interesting for her simple desire to laze around peacefully, and then the rest of the cast manifests 2 or 3 personality quirks, but that's about it. not per character, split across. (continued in World)

World: 3/10
The character designs (and the world that's conveyed through them) are especially boring. Dragon girl is a normal dragon in her dragon form and a normal cute girl + horns (sticks?) in human form. Slime spirit girl has no trait reminiscent of slimes or spirits. Elf girl is a normal cute girl with somewhat pointy ears. and BEELZEBUB, THE LORD OF THE FLIES AND ONE OF THE ELDEST DEMONS OF THIS REALM is a normal cute girl with horns and slightly darker skin. Not even good horns too. Trust me, i know my horns. When they noted the title of LORD OF THE FLIES i was expectant, thinking this might turn out as an interesting character. Yeah, i know i'm naive. For the rest of world building, we haven't really gotten anything yet besides the start and character introduction, but i'm sure we'll get more as the manga goes further.

Theme: 6/10
Effortlessness. Now, now, that's not pejorative, let me just explain. The whole vibe of the manga turns around the idea that persistent, patient effort is much better both productivity-wise and health-wise than straining, rushed effort. And that is already conveyed expertly in countless ways throughout the mere 9 chapters. Gotta give praise where praise is due, in that aspect the manga is one step above most anime/manga. The problem here is that this theme turns into a double-edge. It's BECAUSE Azusa (just checked the mc's name) refuses to leave her home that problems come to show up at her doorstep (literally) and the very things that make this story bad are the embodiment of this general theme. Repetitive plotlines, boring art, unoriginal characters and world, it's like the author just filled in countless blanks with "meh, i'll figure it out later". Then again, "persistent, patient effort is much better both productivity-wise and health-wise than straining, rushed effort" so maybe it'll get better as it goes on. At chapter 31 i'll delete this review and write a new one. Or maybe I'm the problem, maybe I just can't get it because I'm an autistic NEET who hasn't worked a second of his life since he dropped out of high school 2 years ago. ¯_(ツ)_/¯ .

Overall: 5.16 / 10
0.12 worth of bad
0.28 worth of good

Recommendation & Closing Statements:
If you haven't read it yet i think "Kobayashi's dragon maid" is better (horn-wise included).
If you have read it then i think you can read "While Killing Slimes for 300 Years, I Became the Max Level Unknowingly".
Humanity will end in the next 20 years, so don't overwork yourselves, ok buddies?