As far as the sci-fi genre goes, Interstellar is just about the perfect film. It's got everything from an awesome, gripping plot, fantastic visual effects, memorable dialogue, strong characters, and a healthy sprinkling of love ... although that bit about love being an interdimensional quantity went a bit over our heads.
The one thing the film can be said to be lacking in, is a villain.
Sure, Dr. Mann tries to mess things at one point, but he's much better defined as an emotionally unraveling space loony than an actual villain. Sure, you could argue that the plot doesn't need a villain, but what if there was one? One that was right in front of you all the while, only to pass completely unnoticed?
Of course, given that the villain isn't one that is explicitly portrayed as such in the film, we need to examine the setting, context, and facts presented to fully unravel the bad guy.