How about A.S. Byatt's Possession? It wasn't totally epistolary, but I loved the old letters they found and how all the romances and relationships and everything intertwined. And how about Roxanne St. Claire's Hit Reply? My mother didn't even know what an IM was and she still loved it. It was that good.
So what is it about these novels I love? I think it's that they're all about words. There's no stage direction. You can't experience any of the action first-hand. It all has to be told to you at some remove. It's all words, words, words and I do love words.
I slid a little of my love for them into Un-Bridaled. My heroine found a box of old letters from World War II. The letters were based off a box of old World War II letters that we found in my garage. My late husband's father had written them to his sister. I have no idea how we ended up with them and anyone who might possible know was already dead. My kids and I pored over them. They're fascinating.
How about you? Do you love all things epistolary? Do you have a favorite? Do you hate them?