What beginners will always do when playing GnG for the first time is advancing to the right until they get to the Red Arremer. Then they will get destroyed, inevitably, and they will probably stop right there and give up (and I understand, I used to be that guy too). If you do beat him, you'll be "awarded" the first checkpoint of the game. You passed the "tutorial". Does it get easier? Hell, no. But you may discover the appeal of the game: perseverance in front of adversity.

And there's a lot of adversity in Ghosts 'n Goblins. From your encounter with ladder hell in stage 2, to the Red Arremer gauntlet in stage 3, or EVERYTHING in the final stage, no punches are pulled. But it's fine, because the game is fair. Well... Mostly fair. Enemies and patterns are semi-random, so if you learn the stages, you can deal with any challenge properly. The issue is with the semi-random thing, so your job is to play in a way to keep bad guys in easy, established patterns, and not to panic when they act irregularly. Discovering a new level feels like hitting a brick wall, but if you keep probing you'll eventually find your way, and you'll be able to avoid that wall every time after that. Execution and skills are not a problem (thankfully, because the controls are incredibly stiff and unforgiving), if you keep playing and learning, you'll be able to beat this.
GnG is also famous for its gotcha moments (typical Tokuro Fujiwara, really): an extremely annoying one is that you're forced to beat the game using the shield/cross weapon. Avoiding bad weapon drops will become very important in the later stages because of this. More infamous, but not really as bad: you have to beat the game twice to get the ending. If you know how arcade games work, you'll understand it was probably implemented to make looping the game more exiting. Honestly, anyone able to beat one loop can do the second one just fine. The real issue is that it's long and will sap your concentration (especially tough if you're crazy enough to go for the 1CC).

If there's a part where GnG shows its age, it's the platforming. It's bad, like real bad. It's mostly limited to a few parts like the start of level 4, and you'll do just fine after figuring when and where to jump, but the awkwardness will never go away. It was released only two months before Super Mario Bros., but it feels like a decade away here. So if you needed more proof to understand the importance of SMB in video games history, here's another one.

So yeah, Ghosts 'n Goblins. I love that game almost as much as it hates me (it's not an exclusive relationship, it hates everyone). It's honestly a tough recommendation, and I think most people won't like it because of its sheer difficulty alone. Still, if you're up to, try to challenge the first checkpoint. And then maybe go a little further beyond... It might just be your thing.