See now you're somebody whose impressions I'd be eager to hear since I know you were looking forward to Interstellar even when it was back on Spielberg's backburner.
Writing on my phone right now, so this will be brief-ish.
Overall I quite liked it. It's a nice emotional story of a man's relationship to his children, particularly his daughter, with big sci-fi ideas splashed around. I think that core of the movie works very well throughout and hits home hard at various points.
Some of the crazy sci-fi stuff gets stretched thin in terms of logic and/or internal consistency, but it's not that big an issue for me. That kind of comes with the territory when dealing with wormholes, black holes, time dilation, etc. Maybe some of that could be tightened up, but it at least works as a good skeleton for the emotional arcs, and it works moment-to-moment pretty well.
I do wish the overall mission were treated a little more professionally within the universe. It's a bit cavalier. I think the 20-40% range of the running time suffers from characters acting a little dumb, although this is mostly in conversation so it doesn't have big plot impacts. I suspect it was done to cut to the chase and not have a mission prep sequence, but it results in characters discussing and weighing plans and options after the mission begins, and it comes off silly. This is a mission to save mankind, I'm pretty sure you'd have your priorities, parameters for success, contingencies, etc, in order before launch. This dissipates once they're through the wormhole and variables start changing, but I would have appreciated more professionalism from the team at various points.
As has been said by others, there's less big grand space scenery than expected, but those moments are fucking amazing. Often these involve staggering juxtapositions of vast stillness and intense activity, which is fitting and awesome.
And I'll say this. I'm glad Spielberg didn't end up making it if only because I can imagine Kaminski's overbearing love of backlighting being obnoxious. He would have had ample diegetic reasons to crank that to 11 during some of the core emotional sequences.