Tl; Dr: Bro contemplating existential crisis while getting ONIMAI'ed. However, it is a serious story and can get heavy at times. And there's not a lot of light hearted moments. The pacing and build up doesn't make thing go smoothly. It might not seem that way in the beginning but there's going to be a lot of angst later on. The author uses the ONIMAI status to create dramas and "betrayals" due to characters scheming and sometimes you wonder whether the author can give the protagonist a break. (The MC is a competent goodytwo shoes thrusted in a world of schemers and backstabbers)
Before chapter 100, it had a rather simple easy to follow plot, then the mind tangling politics started to slip more and more to central of the main plot. (Hello has this become GoT or house or cards??)
It's very action heavy, sometimes the other bits maybe too much. The author also uses a lot of exposition to make the non action parts work, which I do not find engaging but a lazy decision (and mind you, I do enjoy psychological warfare series but the way this author integrated these instances ain't it, instead of making it seems hype they just seem like a burden to go through in THIS series due to the vibes not having a seamlessly transitioning focus).
Also, character design-wise, lots of characters have similar features so it gets hard to distinguish them (specially from chapter 221).
It's not too hard to read, but events and developments feel like deus ex machina in how they appear and get resolved.
There's also a lot going and scheming of the main plot, but the author is making the protagonist multitask (e.g. getting cursed in a life threatening way, yet simultaneously still have to deal with his sister getting cursed at the same fucking time, while there is a hidden vampire clan conspiracy) and it feels kinda direction less at times because of that. In the beginning before chapter 150 it's better because there's less incidents like this, but it worsens and worsens...
e.g.
Feels random having a 7 years old appear as a 17 years, oh yes so convenient (doesn't even affect plot in the slightest)
Random power up
Random event that JUST HAPPENS to be somewhat linked to the main plot without foreshadowing and build up
Random betrayals after betrayals (so convenient and ez out for the author who didn't bother to set them out properly; imagine GoT and have the Red Wedding event appear randomly without the previous episodes that set the characters---yeah it's that random)
Randomly finding a lost relic or sword or artifact or mind blowing thing without prior leads (oh just so convenient for our MC when he just needs it!)
Instead of managing the issues above with proper foreshadowing, buildups, etc. The author just goes OH YEAHHH IT'S RANDOM_EVENT_ABOVE TIME. I find it personally jarring, and "ok, here's that again".
There's also a waste of potential in developing the side characters, because they don't really get much scene time (I'm talking about the main live interest), who is a run of the mill violent tsundere. Well it's rather good for me because I don't like tsundere anyway...
And as tradition with Chinese scrolling comics, the author doesn't shy from killing characters.