I just happened to be at Toys 'R Us when they ran a small promo displaying Guitar Hero: On Tour this past Saturday, and while initial skepticism kept me walking past, the Guitar Hero in me brought me back. It would be a great disservice to you guys and myself as a gamer if I didn't give any game a chance before drawing conclusions. So I gave it a shot. My first impressions? Not too bad.
Let's ignore the fact that you have to purchase a single-use peripheral to play the game for the moment. My first reaction was that I was playing Jam Sessions with limited input and freedom. Thanks to games like Brain Age, holding the DS on its side doesn't feel unnatural at all, and pretty soon I was comfortable playing. Since it's a touch screen with no resistance, I sometimes wasn't sure if I was strumming the strings correctly, but there's little room for error - I mean, it's a small touch screen after all. Audio is a bit lacking in strength, and definitely warrants use of headphones. And despite its use of 4 buttons instead of 5, there is an expert option which, I presume, is harder than the rest.
As for the gaudy peripheral? I can't say I object, since I did purchase a DS paddle for Arkanoid DS and Space Invaders Extreme. I only presume that there will be much more games to utilize this device because if not, then this is truly a one-time-use purchase.
Overall, the game does what it claims - gives you Guitar Hero in a portable format. You still feel like you're playing a guitar (even though you feel like a cross-eyed dope strumming on the right side while looking at notes on the left). Unlike the DS paddle, however, it's only good for one game, so it's not a purchase I'm willing to make.