Goblin Slayer is kinda entertaining. It's not entertaining because it has a compelling plot, or any deep themes, or any multi-faceted characters (dear god no). In fact, it lacks any depth whatsoever and can be aptly described by its title.
It's a manga about a dude killing goblins. That's it.
There are goblins in this established fantasy world, and they wreak havoc every day by pillaging villages and raping women. This actually happens on a daily basis, but because there are worse problems in the world (problems which are never elaborated on) and because the rewards for killing goblins are too meager, most higher leveled adventurers don't bother to kill them. Instead, beginner adventurers attempt to kill the goblins, but many of them perish in their attempts due to their inexperience and get raped and murdered. But there are worse problems in the world and goblins are apparently too weak (which they are clearly not) to be considered a threat, so this happens daily. Already you can probably already tell that this manga doesn't have the best writing, but alas.
Insert our badass protagonist, the fabled Goblin Slayer, whom bards sing of and people fear. He has made it clear that his entire purpose in life is to kill goblins- he lives for it and knows everything about the hunt. He knows literally everything about goblins, from how they eat to how they move. He has plenty of experience destroying goblin nests and doesn't flinch in killing even the children. He reasons that the young surviving goblins become truly strong when they grow up, and sparing them is extremely detrimental. So he crushes them (literally).
That's it. This dude kills hoards of goblins because of his "tragic past" involving them (a past he suddenly elaborated about without ever being asked early on in the manga.. talk about subtlety). And women love him. How could women not love him? He's the best goblin slayer around.
That said, I enjoyed it. It's fun, despite the entire thing being about killing the little green cunts. The goblin slaying is often done in creative ways, and the protagonist comes up with kinda interesting plans in destroying the things. It's also enjoyable in just how brutal he is at times. At some point, I genuinely wondered why the author was so fixated on vilifying and destroying goblins. Did a goblin murder his family? Did he read a doujin with them and his favorite female character? Does he just not like the way they look?
In all, I give Goblin Slayer a 6/10, which is pretty damn generous given the many negative aspects of it. A more objective and fair rating would be a 3/10 or something of that reign, but I don't really care. It's far more enjoyable than other "turn your brain off" manga like most battle shonen because the author of Goblin Slayer realizes the only entertaining aspect of these things is the ridiculous fighting scenes. There's no protagonist I want to strangle, there's no stupid "friendship is power" monologue and no plot whatsoever. It's a manga about a badass and his genocide against goblins and I like it.