Reddit mentions of Letters From The Earth

Compare Brunner's epic The Sheep Look Up with Margaret Atwood's Oryx and Crake. (If Sheep Look Up proves to hard to find reasonably, substitute Shockwave Rider, also by Brunner.)

Or, if you're feeling really froggy compare Mark Twain's Letters From the Earth with one of his more popularly acceptable works like Huck Finn or Tom Sawyer.