FSE has become a very touristy sideshow/carnival like walk-around with street performers, artists, and the like. In many ways, it's true to the original spirit of Fremont Street's no-shame casinos, especially with girls dancing on bars, and the like. They do have some surprisingly good bands play for free here, so check the calendar for when you're visiting.
Don't expect an elegant experience. It's lowbrow fun, take it in that spirit. If you're up to it. Slotzilla may be the most unusual zip line experience you'll ever have.