A bit late but just in case you haven't watched it yet and are still in two minds I would say give it a go.
It is atmospheric although at times shlocky due to some terrible acting and poor, although never unambitious, set design. Marins himself is gleefully camp as Coffin Joe and is clearly having a great time in the role. He hams it up to the max with lines like (taken from the quotes setion on IMDb due to a fuzzy memory) "What is life? It is the beginning of death. What is death? It is the end of life! What is existence? It is the continuity of blood. What is blood? It is the reason to exist!" He mustn't be taking himself seriously and we shouldn't either! I don't think the film is in the slightest bit scary, it is just good fun (kind of like a ghost train, which a lot of the sets resemble). I don't think it would be half as regarded if it was an American or British production, as we all know some elitists would claim to enjoy subtitled films more than they actually do in order to appear sophisticated. Despite going the creepy atmospheric route it also has some rather shocking and gory scenes which are way ahead of it's contemporary counterparts. At the moment I am having trouble differentiating between At Midnight I'll Take Your Soul and This Night I Will Possess Your Corpse in my head, although I enjoyed them both and would recommend them to somebody who already has an interest (such as yourself).
I'm just a bloody normal bloke. A normal bloke who likes a bit of torture.