
So real. It took me 3 months to read Lotm, I was reading COI, but I took a break to read another series that my coworkers recced (dungeon crawler carl)... I'm also in the dead middle of ORV, and there's 2 BL, a very interesting Korean novel one, and Erha (which is infuriating so far btw -.-). Most of these I'm half way through before I got sidetracked with another story. Time? Hello time? Do you exist? Can you go slower? I have books to finish!!! (Starts global examination manhua anyways instead of finishing dungeon crawler carl...)

I'm only on volume 2 out of 8. COI is a chunk smaller than LotM but still a massive series. In my opinion, the author created a world, and the main characters are just there to explore the world. The world is the basis of the story, not the characters (though I do miss Klein and all of his "this is reasonable"s).
Lumian is a very different person. And COI is a very different plot. I enjoy the snippets back to the original LotM, while tarot card members aren't super big, they still exist and you see them semi regularly, just never from their prospective anymore, or at least not yet... I just realized we rarely ever leave Lumian's POV... He doesn't have a side cast like Klein did, where we follow them heavily too. Or at least not yet. Relatively speaking, I'm still starting this series. So I can't say later on it gets great or anything, I honestly don't know.
If you love LotM, love the lore, love the world. I very much think you should read COI and see where the world goes. But don't expect a Klein 2.0. Enjoy the fact that it's different. Lumain is a really fun MC in his own way, he's just definitely not Klein. Much more witty, funny, and sly. Cuttlefish said that lumain starts out so far away from Klein specifically to write about some world building he couldn't with Klein because klein didn't explore these areas of the map :P
I think in every genre, in every media, when there's and adaptation or a sequel people get angry that it's not exactly the same as the original. Those are the people who aren't happy. There's not as many important side characters, our favorite characters from lotm aren't there all the time anymore. It's a different story. With a different caste of characters. But that doesn't mean it's bad, it's just not the same. And that's okay. I've loved what I've read so far, and I like lumain.
TLDR: I haven't read enough to tell you if it's good, from what I've read so far I've really enjoyed it. I think you should read it if you've got the time :).
I have to reread lord of mysteries, now apparently I have to read this novel too cus the manwha skipped sm details man rn i haven't finished reading my 150+ chapter danmei I started months ago