The best review of Clarissa I've ever read was in The Little Bookstore of Big Stone Gap by Wendy Welch. In a chapter called "On Recommending Books" she writes:
Jenny hates this book with the passion of a thousand flaming suns. "By a third of the way in, I was hoping she would kill herself. Living in a whorehouse without knowing it? She is so stupid she deserves to die. Die, bitch, die!" Thus spake the gentle Southern belle we have seen cry over little frozen birds in the snow. Again, no one tried to save this novel, one of the longest in the English language. Instead we asked why Samuel Richardson wrote it in the first place. None of us knew for sure, but when someone snidely suggested he was getting paid by the word, we figured that had something to do with it.