"If you've played any other karaoke video game or have done some singing in Rock Band, then you'll have a pretty good idea of what the vocal part is like in World tour. The lyrics scroll across the top of the screen along with a set of bars that indicate the relative pitch and duration of each song note. As you sing, an on screen indicator responds to your voice and your goal is to sing at the right times and at the right pitch to hit the notes with the indicator. The indicator in World Tour trails a comet-like tail behind it, which makes it a bit easier to keep your pitch consistent. Overall, the vocal part of the World Tour is pretty close to what you find in similar games. It's fun when you have a full band, but I wouldn't get the game just for the singing portion.
There are a number of minor changes from Guitar Hero III in World tour. Some are good such as new character animations and the removal of the boss battles. Others are not so good, such as an overly spastic background camera that is at best annoying and at worst will cause those susceptible to motion sickness to toll their cookies. Overall though, World Tour is a nice evolutionary step for the Guitar Hero franchise, and it's safe to say that if you're a fan of the series you'll enjoy World Tour."