I'll admit that when I first heard about On Tour, I was sceptical of how the console style of gameplay would adapt to the DS, and I must say that technically, it's transitioned very well.
The core game is much the same as its console brethren; hit the notes as they scroll toward you by holding the appropriate "Fret" on the Guitar Grip peripheral, and strumming the guitar strings as displayed on the touch screen. A guitar plectrum shaped stylus is included with the bundle, but the regular DS one works just as well.
The number of buttons on the Guitar Grip, has, for obvious reasons, been reduced to just four, from the standard five. While this may not seem like a big change, it does have a significant impact. With only four buttons, all of them can now be reached without moving your hand. This saps any of the difficulty the series is known for. It takes a few songs to acclimatise yourself to the new style, but after that, I found myself getting five stars on the final setlist on Expert, when I found myself struggling to complete even Hard on the console games.
To say that the game mechanics have transition well to the small screen, however, is not to say that the fun has. I would imagine that most, if not all, prospective buyers of On Tour have played at least one of the fully fledged Guitar Hero games. For me, as a long term fan of the series, the attraction has always been in the simulation of playing a real guitar, something which the console controllers convey rather well. Here, however, all that is lost. All illusion that you're a famous rockstar entertaining thousands is gone, along with the guitar in your hands. Replacing it is a cramped, uncomfortable piece of gear that feels awkward after one song, and downright painful after five. It's been said before, and it bears saying again: The Guitar Grip causes serious cramps. Of course, this could just be me. I have fairly large hands, although my 11 year old younger brother also reports comfort issues, although whether due to endurance, or the problem being lesser for smaller hands, he can tolerate for far longer than I can.
For me, Guitar Hero: On Tour is a prime example of where video games stop being fun. Without the guitar peripheral of previous versions, there's nothing to distract from the fact that you are, in essence, pressing buttons in time with on screen prompts; simplistic in any situation, but somehow ignored in the rest of the series. Add to this the cramps, the primarily voice activated Star Power (So you look like a lemon playing it, especially if you use the game's suggest command of "ROCK OUT!"), and the overall poor quality of the sound (Remedied to some extent by a decent pair of headphones), and you've got more of a chore than a video game. All that On Tour inspired me to do was boot up the PS2 and play Guitar Hero III again.