Overhyped? Probably! But I for one felt that the movie was quite good. Now I don't claim that I understood the whole "physics" of it. So don't count me among those smug people who belittle the haters saying they don't understand the science behind the whole movie. I mean, seriously, I can't quite wrap my head around the whole space bookshelf thingy and coding the solution to gravity into that watch (and for murph to actually find the watch and figure it out! The odds where overly in favor of humanity it would seem!).
But you've gotta give credit for the visual effects and all the edge-of-the-seat moments that the movie had. All in all, it was an entertainer and I got my moneys worth. And like hawkeye said, this movie depicts some of the basic human nature like never before - Selfishness and Survival Instinct. Like Matt Damon says in the movie, it's hard to judge him because no human was ever tested like he was (though I suspect he signed up for Martian so that he can redeem himself for being a total jerk). In hindsight, Coopers "sacrifice" was just so that HIS family could survive. The rest of the world getting saved was just the icing on the cake (like Bruce Willis in Armageddon). I would like to see him do that if he had no one he cared about back on earth. So one could argue that Cooper was also selfish in his selflessness.
But at the end of the day, its a movie made to entertain people and the fact that people feel so strongly about the morality of the characters involved is proof enough that the write/director was successful in creating a lasting impression for the movie among his viewers.
PS: Funny that you should mention Hans Zimmers music. Even though I thoroughly enjoyed the music, I was reminded of the honest trailer for Interstellar ("The music felt as if Hans Zimmer fell asleep on his organ" ;P )