The whole premise of "a girl sees spooky ghosts and is scared but keeps her cool" sounds like something that would wear itself thin almost immediately—and indeed, that is exactly what happens! The situations keep repeating themselves almost one for one: Miko notices something odd but doesn't really do anything about it, a spirit approaches her and starts questioning whether she sees it (they are, apparently, very inquisitive), she maintains her poker face while being terrified on the inside, spirit goes away, Miko moves on with her life until she runs into another one. That's it—that's the formula. The very few exceptions either have the otherwise very distinctly looking spirits inexplicably mimicking regular people so Miko doesn't realize it, or she just attracts their attention on purpose. At no point do we receive any indication that her past experience has somehow taught her anything, or that the encounter has actually affected her to the point where it would affect her life going forward. Nothing ever changes, and Miko adapts to her life of being bullied by ghosts immediately. If you add it to the fact that why or how she acquired that ability is never explained, you end up in a situation where it's nothing more than a tacked-on gimmick rather than a plot device used to its true potential.
It doesn't help, either, that Miko's character is a walking lump of contradictions. Her internal monologue suggests she is scared, but she doesn't really act the part. She pretty much never fails to keep her cool in the face of unspeakable horror, but such mental fortitude comes seemingly out of nowhere (is she secretly a Navy SEAL?). She drops her phone out of shock when it starts behaving erratically, but does well not to flinch at the grotesque imagery that presents itself to her at any other time. Miko's friends are almost completely useless and do nothing except providing occasional comic relief. They never seem to notice how terrified she is, let alone confront her about it. They are non-characters.
It could be said that it's made this way because it's meant to be played for laughs. Except nothing about it is funny unless you're easily amused by all sorts of gluttony jokes and distressed girls on the verge of mental breakdown—in which case, please go see a doctor about it. I think comedy and horror are a very difficult combination to pull off in general because the emotions that drive them are almost polar opposites of each other. So in the end, you either get something that is too funny to be scary (as it happens most of the time), or too scary to be funny—but never both in a similar measure. Works that successfully balance between the two to ratchet up the excitement just enough before changing the tone can probably be counted on one hand. Nevertheless, Mieruko-chan is eager to do both... and, predictably, fails at both. And it's paced so dreadfully that if you were to start watching it at 125% speed, you'd only notice something was wrong during the OP/ED sequences.
I'll give credit where it's due: *some* scenes have unexpectedly solid cinematography and sound design, and they capture the horror atmosphere pretty well for an anime... That is, at least until the camera decides to focus on one of the female heroines' tits, ass, or thighs, with buttock curves, panty lines and cameltoes well defined—and it lingers there for many seconds on end. The manga is somewhat guilty of this as well, at least in the early chapters, but the TV adaptation takes it to entirely new and completely unnecessary heights, courtesy of Passione—the studio that made its name on some of the more degener— ahem, "cultured" TV series out there. Yeah, the word is still used ironically in this context, but you can already get the feeling that very soon this will become its primary meaning.
I want to underline just how intently Mieruko-chan is willing to die on the hill of misplaced erotic titillation: every few minutes, as part of building up dramatic tension, you're forced to look at a vulnerable underage girl from some of the least appropriate angles just to funnel that elevated heart rate into something else entirely. This is easily the creepiest thing about this show by far. In case I'm not being clear enough on what the problem is and how it's different from a typical instance of fan service in an ecchi anime: a brief panty shot or boob slip in a setting where the mood is light and the girl in question is largely in control of her situation (in other words, it's safe for both her character and the audience to assume it won't escalate from there) is one thing. But protracted, persistent creepshot angles in a setting when the girl is vulnerable, afraid, and clearly unhappy, and we expect it to go downhill for her—that is completely different. The kind of difference that separates a joke made in poor taste from being on a list of registered sex offenders.
It's important to understand this difference because the end result seen here just feels bad in a very irredeemable way. Why in the world would anyone who is mentally healthy be aroused by the sight of a visibly uncomfortable, distressed girl? Is her sexual performance somewhere in the first hundred of questions you might be having at that moment? Do you find being bullied or terrorized somehow cute, romantic, or funny? If so, again, please go see a doctor before it ruins your future relationships or, god forbid, someone else's life. I'm sorry; I'm at the age where spooky scary skeletons do nothing for me, but realizing how many people get off on this drivel is truly disturbing. Fascinating how the series itself is less scary than the thought of dealing with someone who gave it a 10. Miko is a victim in the spirit encounters presented, and most of her actions are just mitigating the damage already done to her mental state. It's not exactly a funny subject, at least if you think about it for more than half a second. Personally, I find it the opposite of funny: it's actively making me unhappy.
Sure, it gets a tad better near the end, like around episode 10–11, when Miko finally starts taking some agency to behave like a protagonist in her own show, and the director—the Interspecies Reviewers guy—becomes slightly less of a creep. The problem is it merely gets from the level of a raging dumpster fire to being almost mediocre. "Better" doesn't mean good; it's far from good. Should you read the manga instead? Eh, perhaps—as far as I'm concerned, neither is worth the time, but the TV series stops at the point where the manga just about gains the semblance of a plot. If this show ever gets a second season and gets rid of the pervy cameraman syndrome, I can imagine it becoming comfortably mediocre. What I find truly puzzling is the glowing reception the series had gotten long before it even started to attempt delivering on the potential of its premise (and mind you, the manga at almost 40 chapters in is still nowhere near where it could've been if written by a competent author). Seriously, if you want good monster horror, try John Carpenter's The Thing or maybe David Lynch's Eraserhead; enjoy your nightmares for weeks. If you want a comedy, try literally any comedy: if you laugh even once, chances are that's already more than Mieruko-chan can get out of you. It attempts to do a lot of things that are completely opposite to each other but does none of them well—not a single thing.
Lastly, there are some very misguided comparisons floating around between Mieruko-chan and Natsume's Book of Friends. The idea is so wonderfully asinine it deserves its own paragraph in this already long review. So let's get this straight: the two are nothing alike beyond the most surface-level similarity. Natsume is a very kind-hearted series with a pronounced feel-good vibe and a great deal of respect shown to all of its characters. And while it also tends to succumb to the "monster of the week" formula with little to no overarching development, the protagonist shows a great deal of agency in how he goes about solving the issues he is presented with in almost every case, with his friends meaningfully supporting him. Miko doesn't: she's just passively drifting along the similarly episodic plot, doing little other than getting distressed (with no lasting effects) and showing ass—and being none the wiser for it. It doesn't feel good, it doesn't feel appropriate, it's mean-spirited in both form and spirit.
tl;dr scared gurl funey and has nice ass