I enjoyed Inception quite a bit. It has an incredibly well refined screenplay with some really expert narrative tension to drive it along. Pretty fine example of the ability for any premise, even one as trope-driven as a heist movie, to have the potential to still be elevated to something complex, intriguing, and emotionally engaging when done with the proper execution.
As a writer and director he has a particular strength in taking a premise; weaving a single supernatural, scifi, or otherwise unusual element into it; and then encasing it around these strong emotional cores that build some of the most incredibly focused and engaging narratives I've ever seen. My three favorite films of his: The Prestige, Memento, and Inception are shining examples of this and imo certainly his defining works. I feel it's when he strays from this and is more limited by pre-established settings and narrative goals such as in Insomnia or the Dark Knight trilogy he begins to falter some however. They're still largely fantastic films (save for Batman Begins, ehhh), but they just lack the ooompth of his original works.
But yeah, all that aside, yes I'm excited for Interstellar. It beats the drum of my space interests and from what little information that's been provided it does seem to be right up his strong point alley. Even if it's a weaker venture, it's hard to imagine him making anything distinctly bad with the pedigree he's been able to establish.
The only strong warning point I kinda hold is in it's nature as a space scifi, which is a genre with a particular sensitivity to any plot holes and scientific inaccuracy; elements for which Nolan's style just simply isn't completely focused towards. As said, his settings are usually inservice to the emotional core of the movie. This is inverse to much of science fiction, or at least hard scifi, where the world building takes the helm and only later is story attempted to be found within the setting. Inline with Nolan and his brother's style I expect it to go a very soft scifi route, more akin to 'The Fountain' than 'Gravity', however I still expect even more division over this film than the amount that usually crops up over his movies.