All of the info about the RIP Tour is on the official site. Basically, you bypass the regular and express lines for all 8 houses and 2 rides (chosen by the guide), reserved center seats for Bill & Ted, and a bar stop or two or three (including a tour-exclusive bar). You get all of that done within 4 hours without having to think at all about where anything is or what to do next. After the tour, you have express access to the rides (but not houses/shows) until the park closes.
If you splurge on a private tour, instead of 4 hours, the tour goes until the park closes and you can do any ride/house as many times as you want in any order you want, bypassing the regular and express lines every time.