I’ve played this quite a bit with various groups. Always cooperatively, ranging from venerated elders of the board games club to my parents. Always had a decent time. I know there are people who, for their own unspeakably perverse reasons, prefer competitive games; I never got the impression this would be a good option. The mysterious monster genre feels very much a team effort to me, so both narratively and mechanically it didn’t seem that suitable for competitive play. I recall it having mechanics for buffing the monster or blocking the other players’ cards, rather than any direct opposition.
I agree with the Arkham comparison - I would actually call it closer to Arkham Horror (board) in mechanics, but closer to Eldritch Horror in feel. ATOE doesn’t have the punishing feel I recall from AH, where I often felt like you get punished for whatever you do. Like Eldritch, you can boost yourself quite effectively with items and skill upgrades.