Oooo, I finally found someone who has explained perfectly what bugged me about this movie:
http://www.imdb.com/title/tt0816692/board/thread/236652123
rs_marinoff on IMDb says:
Plot exposition: They told us... and they told us... and they kept on talking... every little detail was explained to the point of becoming painfully obvious. Every time something happened, one of the characters felt the need to explain everything in detail and painstakingly move the plot forward. T
here was a point where Cooper pulled out a white board and a marker, for *beep* sake. At the end, they had this marvelous sequence where he essentially traveled to a higher plane of existence, something that nobody would be able to explain if it actually happened, he had this terrifying beautiful thing happen to him and instead of reacting to it, the character felt the need to explain everything to TARS in excruciating detail. I'm really not a fan of that kind of storytelling, as it is not very cinematic and takes away from the overall experience. It's what you don't mention in your story that's also so very important. The mind likes to solve puzzles and to wander a little bit, at least.
If you explain everything to your audience, what's the point, really? This film gets paralleled with 2001 a lot, so let me give you an example. Imagine the Starchild started to explain what it was at the end.
Bottom line, I wanna be mystified sometimes, I don't need to know everything, and Interstellar failed big time for me on that count.
* The Matt Damon subplot was pointless. It added almost nothing to the overall story, except a convenient crisis to move the plot along. That was it. If he had simply told them the truth, they would've rescued him anyway and maybe tried to seed the planet. There was no need for him to lie or whatever. It could've easily been avoided if he had told them he wanted to keep searching for a habitable planet and they had come to some sort of an agreement, where he gets slingshot the last planet, instead of the whole ship.
* Everybody knows exactly what to do, even though they have never seen a black hole before, or piloted a craft that close to it. It just irked me that Cooper had these ridiculous hotshot plans, when he claimed that he hardly ever left the stratosphere in his piloting days.