I just watched Interstellar and I got drunk afterwards, so I'm drunk now, but I feel compelled to offer some very quick and loose impressions while everything is still fresh.
Interstellar started kind of slow, but now that I look back the pacing was actually pretty much immaculate in the beginning. The backstory and context for the main plot are set in stone meticulously. However, I must say that the manner in which everything is almost perfectly paralleled and contextualized might have hurt the film in the end. The juxtaposition of this very grounded lifestyle on earth with the ethereal black expanse of space feels very Malick-esque. Anyway, after the slow start I'm pretty much instantly enthralled from the very first moment the cast hits space. The movie is tense and the imagery is so breathtaking that everything becomes a bit surreal and it forces the viewer to dream and then attempts to realize these dreams. Now voicing my issues is going to hard without spoiling anything so this is going to sound really vague. But the second adversity the crew faces on the second voyage is the beginning of what I believe is most artificial and forced feeling part of the movie. Nolan forces these parallels in such a heavy and terse manner between events on earth and what's going on in space and it lacks fluidity. Then at the denouement there's this event, which some people might find magical, but I find utterly ridiculous that takes place. It forces the plot into this overly sentimental, romantic, and sappy turn that really does a great injustice the rest of the film. It feels like retconns itself. If the movie had found a way to end 45 minutes earlier it'd have much better and more satisfying in my humble opinion.