I only barely finished this book. I picked it up on a whim – Twain sounded like fun, time travel into old England sounded like it could be hilarious. Which it really wasn’t.
The book had its fun moments, but it was also extremely tedious. A contemporary American gets sent back through time to King Arthur’s court, engineers his way into the King’s council because he knows the solar eclipses of the time by heart, and tries to slowly change everything. It honestly read a bit like a bad fanfic.
On the upside, I picked up what constitutes generic old-timey speech in English, and which stereotypes were commonly associated with Americans and medieval knights, so while the book in itself was really not good, it provided a bit of honest world-building for the world we actually live in. Even if you don’t like a joke, you have to understand its context to recognise it as a joke, etc.
If you want to read about Americans in England, and want a castle thrown into the mix, read The Canterville Ghost instead. It was published two years before A Connecticut Yankee in King Arthur’s Court and has the advantage of being actually funny.