The Guernsey Literary and Potato Peel Pie Society*, and was struck again by the conceit of that particular writing technique. For some reason, it always strikes me as the lazy way to write a book. Cobbling together a novel by stringing together letters, journal entries, or blog posts allows the author to skip over the messy bits that can prove troublesome: describing the setting, for example, or creating believable dialogue.
It also means, of course, that it's easy to pad out the page count -- lots of white space in the breaks between the letters (see novel mentioned above for a great example of that tactic) -- or to blame choppiness or uneven quality on deliberate authorial choices rather than weak writing skills. Additionally, it can be a little off-putting to read, as I have in some novels, letters that contain information that no one in his or her right mind would have included in a letter sent during the historical era when the novel is set. Chelsea Quinn Yarbro seized upon the letter-writing device a number of years ago for her St. Germain vampire series, and, let's face it, it calls for a tremendous amount of willing disbelief on the part of the reader to ignore the obvious insanity of characters discussing the downsides of being undead in letters being carried by messengers in Catholic Europe in the Middle Ages, especially when those letters are supposedly written in Latin, and the characters writing them are described as already paranoid about being spied on and/or suspected of heresy. (Fortunately for readers addicted to St. Germain since the publication of Hotel Transylvania in 1978, Yarbro salts the letters throughout the novels like the calendar pages one would see in old movies to indicate the passage of time rather than relying on them alone to carry the work.)
One of the advantages of the epistlatory technique is that it supposedly eliminates the omniscient narrator from the story. I'm not sure that's true. After all, someone is picking and choosing which letters, newspaper reports, journal entries, and other material to include to tell the story -- the narrator is always going to be present in some form. The big question actually isn't the technique -- it's does the narrator, i.e., the book, have a story worth telling? Some epistlatory novels do, some don't.
[*Brief review: 100% mind candy; despite its 1946-coming-to-grips-with-the-aftermath-of-WWII setting, the book is basically a piece of lightweight fluff ideal for reading on an airplane or while sitting in a doctor's waiting room. It could have been published by Harlequin.]
Addendum -- total digression: I am now giving serious thought to changing my profile picture. The Victorian lass above looks a lot better than the demented woman with a pen I have been using.