Guitar Hero III was truly exciting, with a new battle mode that allows you to collect and use various types of attacks on your opponent, requiring them to rapidly press a button or use their whammy bar to counter the attack. GH3 will feature songs from well known artists, such as Glowing Stones, Pearl Jam, Beastie Boys and Guns and Roses. Evidently, the artists have been approaching the dev team to be included.
Also, included as a boss character will be none other than Slash, who came out as a guest appearance for Guitar Hero III and explained that he was interested in the game because he had become quite addicted to playing it in his tour bus.
The game will ship with a Gibson Les Paul guitar controller in the PS3, Wii and 360 versions and a Gibson Kramer guitar controller for the PS2 version - all of which will be wireless controllers, allowing you to thrash around as much as you feel the need to.
This is just an initial impression based on the press conference; check back for more details once I've had a chance to play it in Barker Hanger in the next day or so.