Berserk is a series you'll primarily want to view for the action and raw cruelty/power of the villains. It is a very visually impressive manga and shows all of the grotesque nature of its characters in elaborate detail, and if you cannot appreciate that this manga probably isn't for you. The manga is highly recommended over either of the animes, as they cut tons of the gore (with much worse art) as well as story content. Berserk is such a grotesque series that one of the best villains in the series, Wyald, is so disturbing and violent that he was entirely removed from both versions of the anime.

The main character of Guts is largely generic for the most part, with most of his characterization coming as motivation to continue hacking and slashing the villains that provide most of the characterization and unique abilities. As far as story beyond glorifying villains, all of it comes from one particular climax, the Eclipse Arc, around a third of the way through the series that largely defines it as what it is as Guts' world is turned upside down.

The series would be fantastic if it could actually follow up on villains introduced here, but they have barely appeared since despite all the time that's passed. The longtime recurring villains decay over time from their lack of use. The only real reason to read past the Eclipse is Mozgus' arc, which ends around halfway through the manga. Beyond that, no particularly interesting new villains are used and the author takes many hiatuses, with it being legendary how long he kept Guts stuck on a boat.

Protagonists besides Guts can get rather grating beyond the Eclipse and the second half of the manga, as they contribute nothing to help Guts and largely just have to be saved over and over. It's a wonder why they even travel with Guts or he bothers to save them most of the time. There are some good protagonists before the Eclipse arc who are more developed and can actually fight, but they fade into obscurity in exchange for the new much worse ones.

Despite these faults that take place after the Eclipse/Mozgus arcs, it's highly worth reading up to that point. While there is a decent sized gap between these arcs, you'll want to keep reading just to see what the author makes of the aftermath of all the terrible events, easily keeping your attention. After Mozgus, the series is basically complete.