You don't take Amtrak to anyplace a jet can take you if you are in a rush. Even from Boston to NYC, after taking into account the wasted time getting to and in the airports, flying is still usually faster than the train. But if you are on vacation and if your schedule is flexible, then the train can be a great part of an adventure.
In July of 2017 we took the Lake Shore Limited from Boston to Chicago. For the first time in 12 trips, we missed our connection in Chicago due to lateness. The lateness was not due to any error on Amtrak's part, it was just an unusual combination of the things that can happen when you take a train: