The problem with Interstellar, for me, is the editing. For one, it's way too long and has too many unnecessary scenes. But the biggest editing problem is he always cuts away from the scenes you really want to see, right in the middle of them, and it's infuriating. I want to see them go into the black hole, I don't give a crap about burning crops on casey afflecks freaking farm at that moment. Nolan literally takes the most exciting scenes in the movie, and cuts away to literally the most boring scenes in the movie. He did that with Batman Begins, too. I want to see Bruce ninja training, NOT watching opera with his parents or talking to Alfred as a college student.
His editing is a huge problem for Nolan, imo. But it's weird, because when he gets the editing right, he makes some of the best cut together movies ever. Like Prestige and Memento. Those were edited together brilliantly.