Space Mountain remains amazingly popular after 30+ years. Compared to today's rollercoasters, it's fairly simple. There are no upside down loops and at 28.7 mph, it's not as fast as it's more modern counterparts, but it's the theming that sets it apart. There you are in your rocket ship. You hear that familiar rollercoaster 'clack, clack, clack' as you head up, up, up to the peak. Next thing you know, you're blasting through space.
It's black as night, 'stars' are everywhere and you're in orbit as you careen along the twisting and turning track. 60 speakers featuring "Starry-O Phonic Sound" are installed throughout the attraction, so riders will hear "a zippy musical track, the whoosh of passing asteroids, and the rush of interstellar traffic." Before you know it, your hair's a mess, you're trying to haul yourself out of the rocket and planning on going on Space Mountain again and again.
Space Mountain usually has a long wait. The queue is also a hike. Don't think that once you get inside you'll be on the ride in 5 minutes. Your best bet is using FastPass or heading to this attraction first thing in the morning when the park opens. Walt Disney World warns that this ride may be too intense for very young children. A height restriction of 44" is in effect and children under the age of 7 must be accompanied by an adult. Parents may choose the "switching off" option here, ask the Cast Member at the entrance for assistance.