See, Chesterton eventually converted to Catholicism after moving from a hollow form of Unitarian Protestantism to Anglicanism. Throughout his books there are little jabs at Protestantism in general and Calvinism in particular. He even has some amusingly harsh words for the tradition my family historically came from (Quakerism). Personally, I have come to believe in a modified reformed calvinism and believe that this represents the most faithful approach to the biblical witness available. That doesn't mean I fully understand all nuances of all facets of all issues, but I know enough to satisfy the big issues and I am quite solid in my own faith concerning my position.
Chesterton is so brilliant and such a joy to read that at first I felt positively joyous when I discovered him. Indeed I still do, for it was like finding out that there was another C.S. Lewis in existence, and indeed Chesterton has written more than Lewis ever did. I suppose it has been my experience of learning from Lewis that has helped me deal with some of the disappointments I've found in Chesterton along the way. For though it may come as a surprise to some,
Of course, the elephant in the room while reading Chesterton was his eventual conversion to Catholicism. In my mind I couldn't help but wonder how such an intelligent man could be so incredibly wrong about something so important. Not that I believe no Catholic can be saved, but that the points at which Chesterton chose to believe the Reformation was in error were the very points that mattered so very much (i.e. salvation by faith through grace alone). I have only just started the short book in which he recounts his reasons for conversion, and already I started to get an inkling in my mind that might begin to explain this to myself. It appears that Chesterton was in many ways railing against forms of Protestantism which were innaccurate representations of the positions he rejected. Straw men do tend to fall down pretty quick when shoved. Of course I'm simplifying things, but I was grateful to find a much more comprehensive explanation of this position on the Internet today. James Sauer has written an excellent summary of a well reasoned Protestant appreciation of Chesterton called Chesterton Reformed: A Protestant Interpretation. It is well worth the read and I do recommend it.
Some other interesting concerns I've had while reading Chesterton which I have not yet found good discussions on are his treatment of other cultures. Some is excusable as indicative of the times, but others are important underpinnings of major arguments in works such as Heretics, Orthodoxy and The Everlasting Man. His characterizations of "oriental" cultures seem very provincial and out of touch with reality, and yet he uses the contrast between West and East in many ways to show why West is so very much better than East. Yet it is this misunderstanding of what he describes as Eastern "pessimism" that destroys his arguments even as he makes them. I recall those feelings of unease as I read those sections and the same feeling returns when I read his arguments against Protestantism.
Nonetheless, as with Lewis, when Chesterton is right, he is really really right, and I definitely recommend him to all. I have rarely experienced a more visceral delight than when reading Manalive. That book screams to be made into a play.