Welp, I finally got around to seeing it. I agree with the RLM guys, and the Rottentomatoes score. It's a good film, but not a great one and certainly not Nolan's best. What dragged it down for me was the heavy handed dialogue and issues with the plot. I didn't appreciate the "love transcends space" nonsense, it came across as very corny and out of place in a movie that had established itself as being critical of silly concepts and quite grounded. The pro-exploration stuff also began to grind on me, I realise Nolan wants to really push this message but I feel he was too blunt in doing so.
Then there's the issues with the plot. Time travel always fucks up media that uses it, and Interstellar is no exception. It doesn't make sense that humanity evolved to where they are when Earth was destined to die, so how could they have saved us? Time is portrayed as something set in stone unless you mess with it (as seen in the Tesseract), so it should be safe to assume that the future humans had to go through the same stuff we did.
Black Holes do not work the way they do in the movie. No one knows what is beyond the Event Horizon, but it's probably not a Tesseract that happens to manifest all of your specific memories and allows you to change them, before dumping you in the future next to Saturn. Another issue was the constant cutting from Cooper to Murph during suspenseful moments. It felt contrived trying to create drama with the doctor and lung crap on Earth when Cooper is trying to save humanity. I felt Matt Damon was a bit of a distraction in an already long movie, but I didn't dislike the addition of that sub plot.
That said, it did have great imagery and some cool directing choices. It certainly wasn't a bad movie, but I think Nolan could have done a lot better than he did.