Spent a few hours here during our last Key West visit. The building is a beautiful piece of architecture. The wrap around verandah features life-size, realistic looking statues. Inside there are excellent exhibits featuring Key West history including Hemingway, Sanchez, hurricanes and the Spanish War.
Many resorts offer free admission tickets or have buy one - get one coupons. Standard admission is $7 for adults, cheaper for seniors, adults and AAA card holders. Well worth the price of admission.