8MM probably only got greenlit due to the success of Se7en. Like Se7en, 8MM explores the existence of people who are simply pure evil while the main character wants to know why they are like this. 8MM doesn't provide many answers but it also isn't thematically complex. It follows a standard whodunit plot. While Nicolas Cage gives a solid performance, there are times where he takes us out of the story with his signature freak outs. Joel Schumacher manages to create a gritty tone but he has a rather bland style.
Regardless of its flaws, 8MM is still a decent movie. It prefers plot over exploitation and story over violence. For those reasons, I recommend it.