To reopen this discussion, it seems to me that Interstellar is pretty good science fiction. I'm not saying anything about the movie-as-a-movie, that's quite subjective, I just mean what "big ideas" does it introduce into the collective consciousness about possible science fiction memes. Usually a single "big idea" moves a science fiction movie forward, but here I would say there are no less than three big ideas. I'm curious what people's comments are on these, after reflecting on their potential significance: (spoilers follow)
1) That traversible wormholes could be possible. OK that's not really so new, but what's new is to get the scientist who basically discovered how traversible wormholes might actually be possible, involving actual general relativity solutions, combined with some highly speculative elements (basically, some kind of manipulable exotic matter that has negative energy and can be fashioned into structures of singularly high density). If you can put one of these together, then a potential solution of GR would allow a compact 3D region to serve as a kind of "portal" to another universe. Or, to a similar portal located some huge distance away in our own universe, though that actually would seem a whole lot more difficult to do (how do you get to the other end to create that portal?). It seems to me the "big idea" hangs together better if you just make the portal and pass through it, and end up wherever in some other universe. But this is a science fiction movie, you do all kinds of things to have the plot you want.
2) That for humanity to survive on timescales like the age of a star, instead of the million years or so that species normally get, it will need to solve the problem of time travel, so it can use future knowledge to stave off extinction events. Of course this produces paradoxes, as many movies have attempted to navigate. Interstellar takes the view that if time travel occurs, then events that happened already cannot be changed, but information can come from the future which affects the time stream going forward. The interesting wrinkle here is that it produces a consistent loop where advanced evolution becomes possible because of that backward-propagated information, and it is the advanced evolution that also allows for it. Never mind the paradoxes, as time travel goes, that's not bad.
3) The key to make the first two "big ideas" work is to gain access to a region where quantum mechanics meets gravity in a big way-- the singularity of a black hole. Of course it has to be a supermassive black hole for humans to gain access to it without spaghettifying and so forth. How to get out of it, once into check out the necessary data, is a pretty big problem that in my view is the main scientific problem with the movie-- even Kip Thorne doesn't provide any equations to explain how that got pulled off. But I guess if you hold that new physics will be discovered when gravity is married with quantum mechanics, you can do anything you want. That's the most science "fictiony" element of the movie.
By the way, it seems to me that the gravitational time dilation issues raised by the movie were not actually very relevant, it was all just dramatic plot device. The discovery of a habitable planet could have occurred by a second wormhole that had nothing to do with Gargantua, indeed it would probably be easier to imagine a triangle of wormholes where you use one to get to Gargantua, gain access to the quantum environment that let's you learn the new physics you need to manipulate gravity, evolve into 4D beings or whatever, and send the information backward in time to save humanity in the first place, then create a second wormhole from there to some habitable planet, and go there and make a third wormhole that comes all the way back to Earth. Then when the Earthlings figure out how to transport an entire population, they can use the third wormhole and go somewhere nice, somewhere that doesn't have gravitational time dilation. So the whole one-hour-is-seven-years business was just a plot twist, nothing more, it really played no essential role in the overall science fiction driving the story. What it did do, however, was give the population a lesson in the malleability of time that may reach more people than science courses in an academic setting.