Beautiful site, but the fort wasn't accessible when I went there (2012). From what I recall, it had been under some sort of renovation since the early '90s, so I wasn't expecting to see much anyway. Therefore: not many stars for the site itself.
However, the surrounding old town of mud-brick houses, date palms, and aflaj irrigation canals (not a part of that listing) was really interesting. Just wandering through the maze of old, nearly silent streets more than made up for the disappointment of not being able to go inside the fort itself.
As for getting there: renting a car and driving around Oman is pretty easy, even for an American not used to international road signs. I didn't have wifi/cell service, but was able to find my way with a tourist map and road signs, so bonus points for making it easy for tourists.