Thus concludes about 15 books that all (more or less) fit together.
You can read the summary here.
In the end, it’s revealed that many events were the work of our favorite robot, thus tying all of the books together.
It’s an impressive feat to tie so many books together, though it gets rather strained by the end of it (a surprising number of people know a lot about Earth, given that all information about it was supposedly lost millennia beforehand, for example).
The books were fun. If someone asked which ones to read, I’d recommend the Robot Series and probably not the rest of it.
Asimov’s vision of the future, as designed by Daneel strikes me as pretty creepy, but your milage may vary. Either way, it’s still an entertaining ride.