Strong lean or weak likely FF. He had some very unfortunate social and political opinions (like Tolkien, but more severely so, partially because more conventionally so in a lot of ways) and Mere Christianity is a fairly facile text--and is to some extent supposed to be. But The Great Divorce is excellent, as are Til We Have Faces and a lot of his academic work.
Tolkien was a monarchist, traditional Catholic, anti-industrialist/rural romantic, softcore libertarian anti-nationalsocialist, apartheid critic. Which of those things do you consider "unfortunate"?
I have read that some people think he was "racist", but that seems based on pretty thin evidence and is kind of a (pointless IMO) standard accusation against most people from his era anyway + he was quite vocal in his critique of apartheid.