Oh, I'm so glad to see someone else who's read this book! I had a very similar reaction: I fell in love with the premise, my expectations were high, I ended up disappointed. I was not as bothered by the language (I'm less familiar with eighteenth century literature than it seems like you are), but this: "but the writing itself isn't good enough for me to just handwave and enjoy; there really isn't much left to enjoy, once you've done the requisite handwaving" is exactly how I felt too.

(Is it uncouth to link to myself? But you did say you were interested in other reviews, so here is mine - scroll to the bottom of the post.)