It's entertaining, but I have several problems with the main characters and dialogue.
The main characters don't question anything. They suddenly transmigrated to another world and didn't question anything. They just said, "Oh, let's Dr. Stone this [thing]," and that's it. There are no hypotheses, internal monologues, questioning, or anything like that. Also, I feel like the characters don't try to change the world; they only try to make money, especially given how they act towards it. Apart from the blatant [racial discrimination] that Poul receives, they don't have opinions about anything else.
They are like:
Oh, look, the streets smell like [unpleasant thing that smells bad]. Well, it is what it is.
Oh, look, people look at me as if I were an [intellectually challenged person] because I don't know these useless and overly complicated manners. Well, I guess it's my bad. I'll learn.
Oh, look, races are separated by hair color and skin color. Well, I don't care, I'm not going to investigate it. I'll just work for 300 chapters to produce more air brakes.
I understand that the characters have to adapt, and it's the smart choice, but I feel that the MCs don't have any conviction towards their past lives and 21th Century beliefs. They act as if they were commoners in that world that suddenly gained knowledge from another world, instead of actually being highly educated transmigrators from our era. They just accept things, and we aren't explained why they accept it. It's just weird, and it feels like they are empty. I don't know how to describe it.
The dialogues are sometimes too specific or weirdly structured. Instead of something being explained through the narrator, the characters explain it. But sometimes, it's obviously structured so that we, as readers, can understand it, which makes the dialogue weird because nobody would talk like that. It's like they are reading a presentation/script.
Also, the MCs act too respectful, let's better say "agreeable", too much, not in healthy amounts I think, and while they have obvious flaws. For example, Poul is sometimes too lazy or too confident, and Jonathan is too passive or aggressive because of his position of being unable to use his knowledge. However, the characters never swear or do anything that a normal person would do, not that I expect every single person to swear or do crazy [thing] or something, but they don't act like normal 30 year olds would do. It's weird how they act, it's just so bland, so simple.
Maybe it's my prejudice towards the societal norms of the past, but I, for example, would have never acted as a "gentleman" according to the definition of the time, not the idealized version of today. Why? Because I believe that how I act is acceptable, not how they acted. Even if it harms my business, why should that matter? I possess knowledge and, regardless of how foolish I may appear, if I have enough money to produce them, people will still purchase my products because they are that awesome, even if I am an eccentric, weird and disrespectful piece of [thing that's really dirty] (for them) (There's tons of examples of weird people that are genius and earned a ton of money). Obviously, I don't expect the main characters to act like I would, but they bent too much, they concede too much, and we aren't never explained why.
(I had to post and delete my review two times because my review didn't appear for... some reason. My bad.)