This movie is absolutely fantastic! I understand everything clearly by the end, though it will be very confusing when you stopped watching it in the middle (but pls watch till the end). I've read the book "And then they were none" way before and kept thinking about the book storyline while I was thinking on who could be the killer; didn't know this movie was inspired by that specific book.
Though I could say; reading from the negative reviews, some people may think some aspects are not possible/realistic but for me, everything make sense at the end.
I love every detail of the movie. Must watch!!