While the ride may be $8 ($4 for repeats or for $12 you can get 3 rides on any of your choice) you do have to pay for the tower entrance, so plan ahead for this.
The ride is the tallest in the world because it is at the top of the Stratosphere tower. The needle on top is the ride, a reverse drop ride in which you are strapped into harnessed seats that do make you feel fairly secure.
They don't really tell you when you're gonna go, the ride starts to lift slightly and then like a rocket you are headed for the stars. It goes up and free falls for about four or five revolutions, so you get a lot of air time and a great view of the strip if you face south. Don't take anything with you in your pockets, you may not see it till you get to the parking lot and it's embedded into someone's car hood.