It was the perfect ending to the series. The Asimov structured it, it was basically a cat and mouse game at the galactic scale. Introduction of Zeroth law of Robotic was probably the most important facet of the whole book.
It is amazing how many things of real life Asimov touched on when the discussion of two robots.

Really liked Gladia in her new role. Felt it it was long time coming and it was about time too.

Daniel and Giskard were brilliant too.

Overall, a really good read.