Second Foundation is, in its style, more similar to Foundation & Empire than it is to Foundation. It features only two stories, one telling the story of the Mule’s search for the Second Foundation, the other relating the same search by the First Foundation. 

Whilst I appreciate Asimov’s choice to focus more on a smaller set of characters again, I keep finding most of the adventurers he writes to be relatively forgettable, and their adventures to be relatively flat (though not lacking some good twists towards their ends). Whilst we are closer to the action, Asimov just doesn’t manage to create a lot of suspense. His characters are just too collected, too intelligent, always choosing a debate over rapid action. You will not find it surprising that his better works tend to focus on detective-like stories. 

I never really liked the introduction of the Mule and his mind-bending powers in what I would have preferred to have remained more of a hard sci-fi series, and his continued presence in the third book was a bit of a disappointment. Arkady Darell, the fifteen year old main character of the second story, is probably the best character Asimov had written to date, standing head and shoulders above the others – but she can’t save the series on her own. She is a sign, however, of Asimov’s development as a writer. 

Overall, while I recognise that Foundation is a massively well-liked series by fans of classic science-fiction, I find the series only so-so. Beyond the first book, which is distant from its characters but focuses on interesting concepts, Asimov writes what is (to me) a set of relatively simple and middle-of-the-road adventure stories in space, similar in style to the likes of Niven’s Ringworld or even Vance’s Planet of Adventure. I find that those kinds of stories don’t hold up nearly as well today as more concept-focussed work from the same age, not the least of which are Asimov’s own Robot-works. Foundation is another one of those trilogies where it would perhaps be best to read the first book for the worldbuilding, and give the other two a miss.