I don’t think Under the Skin was ever intended to “draw in the masses”. :)
But, yeah, I’d definitely say a masterpiece. Brutal, weird, unique, mesmerizing. Also, Glazer’s track record is really astonishing for how different the movies are and how distinct they are: Sexy Beast, then Birth, then Under the Skin. Watching his movies makes me think this must be how people felt as they watched Kubrick’s career unfold.
-Tom