For better and for worse (mostly worse), Eromanga-sensei is the successor to OreImo and its themes of sister-banging. But where OreImo had some interesting things to say about the otaku community, Eromanga-sensei possesses nothing, and is nothing, puerile and creatively bankrupt.
Eromanga-sensei in many ways represents everything that is bad with light novels. It is a story (I guess, if we put aside its flagrantly incestual nature) of a group of twelve-to-fifteen-year-olds who are famous artists, as if adults do not and cannot exist. If Eromanga-sensei was taking inspiration from the scribbles of a bunch of middle school students, its rubbish writing would actually make a great deal of sense.
Stop me if you've heard this one before: the protagonist and a sexy lady, both being inexperienced in the affairs of love, try to imitate romantic situations with one another as a source of creative inspiration. No? How about the protagonist's rival conveniently being revealed as a cute girl who is desperately in love with him? Or the heroine angrily retreating to her room and screaming "bakaaa!" as the camera pans away? See, Eromanga-sensei isn't an anime that is particularly concerned with sharing anything you haven't already seen in dozens or hundreds of other equally brain-dead romantic comedies. (And seriously, if I have to watch another anime with a hikikomori heroine who is portrayed as some goddess of attraction, I'm going to have an aneurysm.)
I suppose the difference here is that Eromanga-sensei is neither romantic nor comedic. It sure as hell is not funny (unless you are the type who thinks burping is the pinnacle of comedic genius), and its 'romance' is merely a thinly-veiled attempt to make it seem somewhat less like masturbation fodder. Fodder which, by the way, has a regularly sexualised heroine who is only twelve-years-old. Let that sink in for a second: twelve-years-old. She is twelve, and the anime frequently displays detailed shots of her ass, her panties, her naked body, and so forth, and even thinks it is amusing to have her friend (who is the same age, by the way) howling about how she loves penises. Yeah. Really.
Even if lolicon pornography does not bother you, it would be an impossible task to claim this contributes to the story or the characters in any meaningful way. It actively sabotages whatever emotional value it tries to create between Sagiri and Masumune's relationship, and makes it impossible to take seriously anything that happens or could conceivably happen. For example, the anime will reveal Masamune's tragic past in the span of about one minute, and then immediately open the next episode with a girl clad in her bikini and flirting with him. Eromanga-sensei doesn't even do the incest part right since it is more concerned with creating some periphery harem for Masamune than it is with developing his feelings for Sagiri beyond "hey I like you lol." It is stupid on the level of KonoSuba and yet has the audacity to pretend without a hint of sarcasm that it is some touching story. No.
It is actually a fairly sad result when compared to the author's previous work, OreImo. OreImo, flawed and infuriating as it was, actually put a great deal of time into making Kirino and Kyosuke's feelings for one another feel meaningful. Kirino was no doubt insufferable, but by the end, you could at least look at her as something more than an assortment of tropes and incest appeal. Likewise, it also went into a fair amount of detail with regards to the life of a stereotypical otaku. It represented Comiket, eroge, offline meetings, and the conflict people can have when they possess hobbies they are ashamed of. It was no Genshikan, but OreImo did at least try to contribute something to the industry with more appeal than "well, gee, banging your sister sounds like a fun idea."
The same cannot be said for Eromanga-sensei, which does and says nothing about the industry. Any moment when it does display the struggles of Masamune's career, it is extremely, unbearably dull, and often propelled by silly plot devices like one of his love interests offering all their royalties in return for Masamune becoming their slave. The whole premise of being a light novel author is an accessory that may as well not even exist. If you stripped all the fanservice away, all that would expose is the show's unsightly skeleton.
I can't think of any situation where Eromanga-sensei could come as a recommendation. It is asinine dreck, without so much as a modicum of creativity. I suppose its colourful art and catchy opening animation may lead some people into thinking the anime is more than it truly is, but it is best to be honest: the sole reason anyone likes this show is because they want to bone the twelve-year-old heroine.
Now how much merit is there in a story like that?
I'd wager not a whole not.