First of all, let's get this out of the way. Interstellar is three hours long. If this is more sci-fi--with a touch of Quantum Physics and Philosophy thrown in--than you are in the market for, this one's not for you. The talk of space-time can be daunting at times but I am a nerd for such things.
Characters - the leads, Matthew McConaughey and Anne Hathaway are terrific, as are the secondary characters, Michael Caine and the two actresses that play Matthew's daughter. They are at once knowledgeable and human. Thus they are flawed. I liked that.
Synopsis - The Earth is dying. A massive planet-wide Dust Bowl called the Blight is destroying all plants. People are starving. Technology is frowned upon. Cooper (McConaughey) is one of the last space pilots left on Earth and he and a few other astronauts are tasked with saving the Earth. Oh yeah, they are traveling to another Galaxy--through a wormhole--to investigate four planets that might be suitable homes for the human race. The planets are marvelous.
The effects are wonderful, but the humanity in the writing is what sells the story. I loved the relationship between Cooper and his daughter. I loved the vulnerability of all the characters especially Anne Hathaway's character. But then again, I think she's terrific in everything she does.
In the end there's a smidgen of space-time hocus pocus but as I said before I love that stuff.
So what can I say but give it a shot.