I also read the first Epic Collection for Moon Knight, which collects all his original appearances. About 90% of it is written by Doug Moench (who vehemently denies that Moon Knight was influenced by Batman, even though you'd have to have never heard of Batman to not see the similarities), so it at least has a consistent quality to it. The stories get better as they go along, though Moench relies far too heavily on 'This new antagonist that will only be around for an issue has major ties to Marc's past!' as a crutch for a lot of the stories. At one point one of the baddies is even Marc's own brother who is never referenced before or after that story (although I think another writer makes use of him later).
The biggest problem with the Moon Knight character at this point is that he has no reason to be a vigilante, let alone a hero. He's not making up for past sins or trying to stop a personal tragedy from happening to someone else. He's not even someone who naturally just wants to do good. The closest they get is that he seeks vengeance against people because a god of vengeance maybe possibly revived him (that part of his origin is left ambiguous at this point). Speaking of ambiguity, Moench can't seem to decide if Moon Knight has any powers or not. During the first handful of initial stories MK's physical abilities are enhanced depending on the phase of the moon due to being scratched by a werewolf (no, really). Most of the stories ignore the goofy moon-based strength stuff only for it to then randomly pop back up later and then disappear again.
The thing Moon Knight is probably most famous for - being mentally unstable and having multiple personalities - isn't really in these early stories but the seeds of it are there. At this point he has four identities he goes between depending on what he needs to do, all of them with their own personalities and backstories he's given them to help better sell them. While he isn't yet crazy you still have Marc or a supporting character worry about his mental health and the strain of juggling the various personalities, with him occasionally forgetting to 'leave' one of the identities when he should.
I got it for around $20, which was pretty good for over 500 pages worth of content. If you're someone who likes the '70s and '80s eras of Marvel it's a decent read. The only technical problem I had with the book is that some of the stories are out of order, though continuity isn't incredibly tight at this point so it's not a major issue.