It is impressive how awful the writing for this manga is. The only component which is decently written is certain segments of a few action scenes and some short generic conversations between friends.
The main character is completely generic, which would not be bad by itself, but he shoves so much cringe dialogue down your throat that it hurts. They also try to do the "Overpowered" + "Constantly considered weak" thing which is a fun trope but they mess it up so badly to the point where you can't really imagine why do people still think he's weak? Like for example people call him weak cause he can't use body enhancement magic but he is stronger than everyone without using the enhancement so who cares? He can't use "magic" but he can do many things which are basically "magic" like creating clones and stuff like that.
By far the biggest problem with the characters are the villains: their stories are instantly forgettable and generic AND they take up sooooo much screen time and the writing expects you to take most of them seriously without justifying it.
The supporting cast is mostly there to prop up the main character or the villains BUT the minor dialogue they get is not that bad. Their personalities are generic too but it's not really a problem since the spotlight switches away from them before it becomes a problem.
The worldbuilding makes absolutely no sense if you remember anything that happened before the current chapter you're reading. They introduce flying brooms for a racing event at school for example but they have 0 impact on the world and no one uses them outside of that contest, so much stuff that would change the world but only shows up when the writer wants it to.
The art is gorgeous and looks especially good when it matters; add to it the fact that the action scenes flow very well and make it easy to understand where everyone is and what they're trying to do in every panel is a big plus. Frankly I think the artist is wasted on this. He's easily in the top 10% of his contemporaries when it comes to quality.
If you want to pick this up you either read it just for the art or have the superpower to ignore awful writing.