The Black Tower

I have to admit I was disappointed by Louis Bayard's The Black Tower. It had a lot of elements I like: mystery, historical fiction, alternative history, gritty detectives, a likable main character. But I just didn't love it. I didn't dislike it; I think I just had really high expectations that weren't met.
I had read several great reviews for The Black Tower, and many compared it to Matthew Pearl's works, which I love. There's even a quote from Pearl on the back cover singing the book's praises. And Bayard had an essay in Maybe Baby that I enjoyed, so I fully expected to love this book and be enthralled all the way home from San Diego.
But I wasn't. I think the language bothered me and kept pulling me out of the story for one thing. Bayard uses current curse words and some slang terms that startled me as I was reading and took me out of nineteenth century France and into modern America. It's an easy thing to avoid dropping the F bomb, so I was surprised he must have purposely included those and a few other words/sayings. It's a small thing, but it was really distracting.
Although the storyline idea was good - the son of King Louis XVI and Marie-Antoinette was imprisoned during the revolution and was thought to have died in a tower, but this book asks, "what if he didn't die?" Intriguing idea. And it was suspenseful until about halfway through, and then I just wasn't engrossed anymore. I took out my iPod and listened to music for a while and just stared out the window, which I never do on a plane. I had other books with me, but I didn't pick up one of those either, so perhaps I was just exhausted from the conference and not able to focus and it didn't quite get a fair shake. Anyway, I kept flipping back and forth between reading and not-reading it the rest of the trip and finished it just as we hit the runway in Oklahoma City.
Has anyone else read any Bayard? Did I not give him a fair chance? I'm curious since I fully expected to love the book.