If someone asks me that question, I will tell them, "I have none."
I have read a number of other people writing about Spencer's work. I have read both condemnations of him as a crude social Darwinist, and defenses of him saying that the first opinion is all wet. But I have read almost nothing of what he wrote myself. And thus, I suspend judgment, until such time as I might get to read him myself.
I cite Spencer only as an example here, in particular, since I am presently reviewing a book that condemns him along the lines of the first evaluation mentioned above. But the author of the book in question has no such scruples: he summarizes hundreds of thinkers in the work (a history of liberalism), and tosses out quite definite opinions as to whether they are good, bad, or ugly. As I often do when first opening up such a book, I looked to see what he wrote about thinkers with whom I am very familiar. I found he had sections devoted to Oakeshott and Hayek, and read through them. I must say, I was appalled. It is fine to criticize Oakeshott or Hayek, and I have my own criticisms of each of them on various points. But it is really not on to sketch a cartoon Oakeshott, or a cartoon Hayek, and then criticize that cartoon.
But the purpose of a book like the one I am reviewing is not too seriously engage the hundreds of thinkers mentioned in it: How could an author possibly do that in a book of a few hundred pages? No, the purpose of a book such as this one is to enable people to sound informed at highbrow cocktail parties or on an "intellectual" Sunday-morning talk show: When Oakeshott's name comes up, the reader of the book can say, "Yes, well, his thought might apply to a static society in which nothing ever changes, but it hardly applies to ours!" The service provided by these books is to provide its readers with a compendium of factoids and prepackaged, soundbite ready opinion, so that they can appear informed, without ever actually having to engage in any serious thought.