There are three parts to this place - the building itself has a scandalous history, there is a video film of Bermuda giving its historical setting and then the larger display of what Bermuda was up to during the American Civil war. If you have any interest in Confederates and Unionists then you will be glad you came; if you know nothing about it you will also be glad you came . My favourite is the board about Dr Luke Blackburn - I shan't give it away, you will have to visit for yourself.
It will take you less than an hour, it is suitable for children but not suitable for wheelchairs - stairs to main museum and steps to shop are unavoidable. The entrance fee is just $5 for an adult.
Note there are no facilities or drinks offered but there is a good cafe across the road and a place to eat alongside the dock around the corner. Don't walk past it - walk in.