This for sure is the most popular tourist attraction in Slovakia. There’s a large car park, a 135 SK entree fee, souvenir shops and you can get drinks and snacks at the inner castle courtyard. Be aware though that like many other sights in Slovakia it is closed between the months of November and April. You’ll have to make do then with the majestic view of it from across the surrounding plains. Which possibly is the best part of the visit anyway.
For those who can get in it is wise to wear sensible shoes. First, there's the uphill walk to the castle itself, and its interior isn't paved either. It's kind of a climbing experience because it's just all ruins. It is possible to climb the remaining residential tower. Some of the best-preserved rooms at the back hold a little museum with the usual medieval castle displays of canons, guns and armour. There's also an original chapel.
I didn't visit any of the towns inscribed together with the castle (bit fed up with churches), but chose Levoca instead. This city about 15kms away is currently proposed as an extension to the Spis WHS. Its central square has a definite Italian flair because of the many Renaissance buildings. But what I really came to see is its remarkable wrought-iron "Cage of Shame". This is where the local 16th-century Protestants kept their women that wouldn't behave!