I'd really recommend the books rather than the series (though the latter isn't bad). Chesterton is one of my favourite writers, and the stories are short and easily digestible.
The Father Brown stories are not easy to read! Chesterton's mastery of the language and turns of phrases makes it quite challenging to understand their meaning. But i believe that adds to the charm of the stories and perhaps maybe the reason why they are not as popular as the Sherlock Holmes stories.
