Big Thunder Mountain is a train-style roller coaster. It's fast, with some dark moments, some loud moments, and lots of twists and turns. The ride lasts 3 1/2 minutes and travels at speeds of 25-30 mph.
Each train consists of a locomotive and 5 cars, and each has a unique name. The trains are U.B. Bold, U.R. Daring, U.R. Courageous, I.M. Brave, I.B. Hearty, and I.M. Fearless.
Each car has three seats, which are big enough for 2 average adults, although I have squished in 2 adults and 1 child when Bean wanted to ride together in the front. The restraint for each seat is a lap bar that goes across everyone in the seat. It locks into place and provides something to hold onto around tight turns as you will slide across the seat. It can be a little tricky if an adult and small child ride together, as the lap bar won't close down tightly across the child, but it's not really a problem if you know about it ahead of time.
The train travels in and out of the mine several times and goes up and down frequently. There are bats and rumbling rocks inside the mine as well as authentic antique mining equipment. The outside of the mountain is reminiscent of Utah and Arizona's Monument Valley.
As you travel around the mountain, you pass through Tumbleweed, an old mining town, where a party is going on in the Saloon, beneath the skeleton of a dinosaur, and partway over the Rivers of America. (If you go to Tom Sawyer's Island, head over to Fort Langhorn where you can "shoot" at the trains on Big Thunder Mountain as they pass by across the water.) For a wilder ride, request the last car on the train, and for a milder ride, request the front car. And don't forget to ride this at night, there are several unexpected sights that can really only be seen at night.
I love Big Thunder Mountain and make sure to ride it every time I go to the Magic Kingdom. This may not be the wildest roller coaster at Disney World, but it is definitely one not to miss.