I was into it early on, but 'Who’s That Knocking at My Door' lost me the longer it went on to be honest.
This 1967 movie is notable for being Martin Scorsese's feature directorial debut and Harvey Keitel's film acting bow. For me, that's where the interest stops sadly. I did like Keitel and Zina Bethune across the opening portion of the 85 or so minutes, for example their chemistry and dialogue works well.
However, by the end the way Scorsese decided to play didn't really work for me personally. I don't actually mind how the story literally ends, imperfectly as it is, it just more so how events get to that point, the whole vibe just felt different and I didn't find it as watchable as what preceded.