Really depends on what you like.

The humour is decent, some parts are even genuinely funny, but the story operates on plot amor, conveniences, and everyone loving MC for no particular reason.

ML is a good guy, while he's a bit pushy at times, there's no abuse, dub-con, or anything else, just a bit of "grooming" if being there for someone 24/7 and doing everything you can for them since they were a child is considered grooming in your mind.
I'm easily disturbed by such things but even I think it was done well enough and doesn't come off as wrong or creepy.

There's no real plot, the original Shou and "mystery" around him is brainless, this part is over before it even really started and makes the whole "cannon fodder in a book" completely meaningless.
I'm not sure why the writer chose this setting when there's absolutely nothing to it.

My main problem is the MC.
He's so naïve and innocent that it hurts, and the biggest pushover you can imagine.
His self-agency is non-existent, everyone shoves him around and he does whatever they want; I'm not a fan of this kind of character and it sadly gets worse towards the middle, his whole life is decided by others, he never resists even when he's clearly not willing to go along with it.
The romance suffers as well, he's an adult too innocent to understand when someone flirts with him and he's too innocent to see that he's in love with someone.
Overall, he's too childish for my taste, like a small kid in the body of an adult man.

It's a mediocre story that doesn't offer anything new, with decent humour, nice characters and good romance, but certainly not for everyone.

This is very standard for this genre - it follows stereotypical plot line of adopted MC realizing he’s cannon fodder and breaking away from the book plot. And as tagged it’s heavy on the doting by family and friends and ML (which is what I wanted to read). So it delivers what’s promised in the summary. It’s okay for the genre and I’ve definitely read better. But it’s not terrible. Only negative I’d say is that the plot doesn’t feel fully fleshed out. Primarily because the main antagonist disappears less... more>> than midway into the story. I did appreciate that we get follow ups on the romance for the brother and the best friend. A lot of the story felt almost like slice of life tbh. Overall not bad. <<less

To me this very much feels like fanfiction level writing and storytelling. Give this novel a try and you'll know what I am talking about (i don't think this is fault of the translation). Especially in the way the characters are introduced (very cliché and cringey imo). I also can already tell that the story is not executed well (MC realizes he's a character in a book because of recurrent dreams and his character is instantely very different than before).

This type of story has been told numerous times so I'd... more>> recommend just reading a different novel with a similar plot. <<less

My review is a little biased since I read this immediately after reading seize the throne and this novel ticked me off in the wrong way. If you want to read something sweet after an emotionally exhausting novel and just switch off your mind then go ahead and read this. Like the other reviews mentioned it's just people doting on the protagonist which I really don't understand because he doesn't really have much going on for him character wise but I didn't finish reading it so I might've missed something.... more>> As for why this novel ticked me off

Spoiler

When the real son first appeared, I really liked him and he was a nice person. I think he could've gotten along with the MC and MAYBE the two of them could've been brothers. But unfortunately some random annoying dumba$$ transmigrated into him and he ruined everything.

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again emphasis on I didn't finish reading the novel so maybe it has redeeming aspects which I didn't get to. <<less