I also saw this at the cinema in the 80s and have never forgotten it, even though I have never seen it again anywhere.
I don't know whether if I did see it now it would seem dated, but remembering the storyline and comparing it to some of the terrible modern films I've seen on Zone Horror I should think it would stand up very well.
I can still remember his coffin sliding out and opening up and all the dead bodies becoming reanimated, and the blue lightning. Having seen hundreds of horror movies and still remembering this one, it must be good.