Yes, it's rigorous. For classes like language and math, you are placed at the level that will provide you with the greatest challenge. There is also good support if it turns out the challenge requires it. The school offers a lot of AP courses. There are 2 math tracks: one takes you into applied mathematics and culminates in AP Statistics and topics in statistics, the other takes you into the Calculus APs and differential equations.
History and English are very strong. I don't really perceive an enforced ceiling at the school; a bright student can take it as far as they want to go. And yes students take the workload seriously. DC is a sophomore and currently in fall term exams. We aren't hearing much but I know he's looking forward to getting home for the holidays and it has been a highly focused and motivated sophomore fall after a more "transitional," up-and -down year as a freshman.