*NO SPOILERS*

Berserk lets you know within its first panel that it's an adult manga and that if you're not ok with that, you should put it down immediately.
Rape, gore, swearing-- anything and everything vulgar is present in Berserk.

Berserk is about a man named Guts and his quest for Revenge against a new god (kinda) named Femto.
As the manga's main premise is set after its first arc, ("The Golden Age" volumes 3-14) it's really hard to not spoil anything for you. I'll have to remain kind of silent about its story, as its surprises and twists are insane, and I want you to get your full experience.

If there's one reason I could tell you to read Berserk, without spoiling the story, it's the art. I can say, without a doubt, that Berserk has the most impressive art of any manga or comic I've ever seen. It is utterly breathtaking.
Its designs are amazing as well. Every armor set that Guts has had is pretty unique, the weapons are really neat, and everyone has a face very unique to them.
The most impressive designs go to the monsters throughout the story. They're unique, grotesque, and very different from monsters I've see in other fictions.
Aside from designs, the characters themselves are also very fleshed out and unique from one another.
I think that what makes a good character is their actions, not their personalities. Berserk has one of the most involved casts out there.
If they've been useless, you can count on them either leaving the story, or doing something of use later.

The only problems I have with Berserk are its inconsistency of tone, and the constant, meaningless rape.
Let me address both: At first you get the feeling of a hopeless world with Guts as its only person with a will to fight. Then it goes to the Golden Age arc, (A fan favorite, not mine,) which is placed before the hopeless feeling world. This one feels like a classic, medieval fairytale. Still dark, but there are prospering kingdoms, and hope. After the Golden Age, it goes to the Conviction arc, (My favorite,) where it's once again hopeless feeling. Guts is alone, trying to figure things out, while endlessly fighting for his life and searching for revenge. Next arc, it feels like I'm reading a video game... Guts meets allies and kind of calms down. He starts to seem like a fatherly figure and feels like the DPS character of your MMO. He's still the main character, but dialogue is coming from mostly his allies going, "How can anyone lift a sword like that!?" "What power! How will he ever defeat this enemy!?" I'm honestly bored of where Berserk currently is. The only thing keeping me with it are its art and the suspense. I want Guts to get his revenge, I want things to happen, but I have to sit behind an MMO feeling for these arcs. (The Falcon of the Millennium Empire arc, and now the Fantasia arc.)
My other previously mentioned "problem" is completely opinionated: The constant, useless rape.
Now, I get that it's in a dark, medieval world, and that back then, if you were a peasant and pretty, you'd be likely to get raped. A lot of times, the rape in Berserk is tied to the story and is important for setting a dark tone, but at some points it was straight up predictable and almost comical. "Oh, female character is missing? I guess they're gonna get stripped and almost (or actually) raped."
I can think of seven times that rape was important to the story, but trust me, many other rapings will occur, simply because the artist loves drawing sex.
I warn you again, there are hentai-like moments everywhere. Sometimes, genitals are shown.

Berserk is an insane ride that's been going since 1990, and I can't see the end yet. If you don't care about vulgarity and you love art, Berserk is a must read.
I apologize for not telling much (Really any,) of the story, but take my word, it's very interesting.