I've been reading The Pilgrim's Progress, and well...don't take this the wrong way, as there's a lot of similar literature to this that I enjoy, but I absolutely hate this book.
Mechanically, the book is not separated in any way, shape, or form. There are no chapters, sections, or such. There are just long paragraphs and a Part One and Part Two, and then that's it! There is rarely anyway to punctually or contextually tell whether who's speaking and how dialogue is transitioned. The narrative is rambling and repetitive.
Style-wise, it is quite possibly the most preachy, uninhibited, self-important writing I've ever encountered. The character is an unfiltered Gary Sue, who starts out somewhat sympathetic but becomes increasingly dull and unlikable as the story descends (irony, haha) into black-and-white conceptualization. There is practically zero subtlety in the presentation, as the whole thing is basically one extended slideshow of metaphors and allusions. Characters are named Pliable and Hypocrisy and Hategood, and what they like, personality-wise? Pliable! Hypocritical! Hates Good! John Bunyan, you just blew my mind.
It's old and supposed to be profound, but I found little actual substance in it, in terms of theology or the idea of salvation. It consistently regurgitates old ideas, dressing them up in thinly-veiled imagery and symbolism. It's antagonistic and challenging, often without backing up its arguments sufficiently.
To think that it's the second most read book in the world boggles the mind. Maybe I'm missing something, but my diagnosis of it is that it's just boring, difficult, and very self-righteous, even for a Christian book. Keep in mind that I thoroughly enjoy Dante's Inferno. But The Pilgrim's Progress? Skip it.