This manga physically exhausted me, because of that I only managed to (force myself to) read 8 chapters. I honestly wanted to read a little more, and atone for the sins I committed in my past life by going through this torture, but I just couldn't. Let's dive in into the abomination that is Exposition: The Mang-uh, I mean, Only Sense Online manga...ahem.

Story 1/10:
There is no story when it comes to this manga. Just the MC logging into an online game and farming for loot to upgrade his skills (aka Senses). All chapters have basically the same 3 things: a) MC crafts potions or an item while at the same time extensively talking to himself about every single process or skill that he uses (WARNING: This part is capable of inducing mild headaches due to the high amount of exposition). b) MC goes and sells them to a vendor, each time surprised at how much money he made only to later end up spending everything in a jiffy, he also sometimes discusses trading and economy (WARNING: This part, too, is capable of inducing mild headaches due to the high amount of exposition). c) MC chats with his friends about Senses, and they make fun of the terrible choices he's made in the game (WARNING: This part is also capable of inducing mild headaches due to the high amount of exposition). Rinse and repeat, over and over and over again.

Art 1/10:
Do not let the pretty manga covers trick you into reading this (like it did to me). While it may look pretty with color, Only Sense Online has some of the most generic character design and art I've ever seen in an isekai manga. While I do not have much to say about the copy-paste character art and design, I do have a some things to say about the backgrounds and environments: You know, I thought Re: Monster's artist was terrible at drawing environments, but OSO just takes incompetence to a whole new level. Background art is basically non-existent, and whenever the artist actually decides to draw something, it is so terrible that it makes me wonder how this was ever approved for serialization. Monsters designs are blocky and would be impossible to know what they actually are if there weren't helpful boxes with the monster names written in them. To give you an example, there was a chapter where the MC was shooting arrows at some birds, and I could've sworn they were seagulls...or something like seagulls...but then again, he was at the woods and seagulls don't live in the woods...I am honestly confused at what those things were. Anyway, buildings are somewhat better off than the monsters, but they are still far worse than anything I'd expect from a manga artist. Sloppy and rushed is what I would call them.

Characters 2/10:
The characters would honestly be fine if not for the dizzying amount of exposition they offer every single time they appear. I'm serious, every time a character appears they start off by offering some random chat about a quest and stuff like that, and their conversation ALWAYS ends up with explaining how to craft something or enchant that other thing, or how Senses work, their various combinations etc. This manga is usually around 35 pages long, and you could spend more than half of each chapter, just reading explanations on how things work, just page after page after page of unrelenting exposition that is done solely through dialogue. It came to the point where I rolled my eyes every time any character appeared, cause I knew it was gonna end in some sort of long explanation about some mumbo-jumbo shit that would give me a headache.

Enjoyment 1/10:
No. No enjoyment. The only enjoyment I ever got from this manga was when I stopped reading it.

Overall 1/10:
The story is non-existent and every chapter follows the same formula. The artist either doesn't bother to properly draw the background art even though he is serializing a monthly manga, or he's just plain incompetent at drawing. And the characters are only every used to offer exposition about this or the other while barely giving the reader any room to breathe.