If you actually want to learn about Pirates, you aren't going to find a better place. If you want blood and guts and stories of vicious dastardly brutes killing innocent merchantmen, keep looking. Blackbeard is mentioned only once, and while you will get the obligatory Captain Kidd legend, it will be disappointing.
BUT, you will also learn why historians believe pirate ships were more democratic than most nations, what really happened to crew captured by pirates, and see with your own eyes real pirate treasure discovered at the bottom of the sea. AND TOUCH IT.
The bulk of the museum discusses the fate and history of the slaveship, turned merchant, turned pirate, turned sunken wreck of the Whydah. It was lost for 300 years, then discovered by a treasure hunter. But his treasure was the artifacts and history of the Whydah; the coins and cargo it carried may get the press and keep the kids excited, but the history that was found is the true treasure.
Unlike many historical museums that show you replicas and fake dioramas and exploitative videos, the bulk of this museum is real. The artifacts on display are mostly from the actual buried wreck of the Whydah, recovered and restored. Some are amazingly new-looking, while others show their age quite accurately. Weapons, cannons, coins, pulleys, anchors .... All the fun things that every maritime-related museum displays are there. But these are the real ones that were stored in ocean water for 300 years before being displayed.
Your kids will love it, racing through and pointing out all the cool things and learning all kinds of things to brag about to their friends, and then they'll complain about having to pull YOU out of the museum to go do something else.