It wasn't a bad movie: it was well put together, the plot was very interesting and easy to follow. However, I think that the story lacks more development: in that more explanation needed to be shown pertaining to what the creature was, where they came from originally, why women of a certain age etc.; granted some explanation was given as to the rational for the longevity of their species, but it still begs the question of the "why" a women at 42 is insufficient?
This coupled with the unanswered questions - at lease to me, of why his species are able to create such a refined and pristine body capable of easily seduce women, how was Libby suddenly asleep: did someone knock her out, was she drugged with the macaroni pie, what the purpose of the women's hair turning red during what seems like an incubation period at the end of the movie?
Inversely, if there will be a sequel that delves deeper into the 'why', then that's acceptable. If it is the contrary and that this is just a 'one-off-type' Si-Fi horror, then I cannot wholeheartedly gave this movie a perfect 5-star rating.