Berserk is... worth it. It has my full recommendation from the beginning. Now to go into details.

I'll have to separate classic Berserk from the newer seasons, since there's a massive difference.

Classic Berserk (Kenpuu Denki Berserk) starts off strong, with a battle between the protagonist, Guts, and a vampire looking demon. Guts wields a massive sword and an impressive looking prosthetic metal arm, with interesting steampunk attachments. The battle is impressive and leaves you wanting for more, but unfortunately any questions you might have about these demons remain unanswered for now.
Instead, the entire original season is a flashback, from Gut's youth, how he fights as a skilled mercenary, how he gets recruited by the best mercenary group there is, gets to fight in a war, and all kinds of other exploits. Only at the end do we really get into the real meat of Berserk, that was only hinted at in the first episode, the fight against demonic forces.
Unfortunately, also at the end, is my biggest pet peeve with classic Berserk, the fact that we are left in a massive cliff hanger, that doesn't get properly resolved even in the sequel series. Instead you'll have to watch the movies (or at least the 3rd one) that literally retell the same story of the first season.
Of course you'll be thinking, "Why should I watch the classic Berserk anime, I'll just watch the movies?". Well, the reason why you shouldn't skip it, is the different animation styles used. The movies have the same aesthetic as modern Berserk, and I plan to talk about that later, so let me first say a few words about classic Berserk animation.
First word that comes to mind might be: dated. Or you might notice the obvious corner cutting. But you know what, it's still gorgeous. Each sword swing, each punch, each hit, feel like they have weight to it. When you see someone getting their get chopped off, you feel it in your gut. The gore feels real. I don't think I can do it justice, but it simply is amazing.

Now about modern Berserk. The story takes a pretty big turn. While the classic focuses on the realities of war, and doesn't deal much with fantasy elements, modern Berserk suddenly is a fantasy story. You get elves, witches, spirits, lots of demons, magic items, and a fanatical religious cult that's obsessed with culling out heretics.
I don't view the story itself as bad, but after coming from the more grounded in reality first season, it's definitely a bit jarring. I wouldn't be surprised if there are people who are put off by the change.
The animation... is simply horrible. Take everything I said just a little while ago, and do the opposite. Nothing feels impactfull. Guts swings his sword, but when he hits something it doesn't feel like it actually hit. They decided to go with CG 3D model animation, but I don't think they really knew what they were doing. The characters look like puppets on strings that awkwardly move around. Lip sync is basically non-existent. There really is no good part of this design choice. And it doesn't get better in time either. You just get used to ignore the bad, if you're lucky and if you actually manage to stick around that far.

What both versions have in common is superb music that gets you pumped up for each battle and good voice acting.

This is one of those rare occurrences where I really have to give different scores between seasons.
Classic Berserk gets a solid 9/10. A must watch.
Modern Berserk... 6-7 at best. But it still has my recommendation, unless you're really not into fantasy stuff.