If it makes you feel any better, I will make the implied "based on this description" explicit.
However, I don't see why you're surprised or indignant at my reaction. Based on what makes Guitar Hero a good game, how can this game NOT completely suck? Instead of a controller which is comfortable and more-or-less resembles an instrument, you have a handful of colored buttons tacked onto the bottom of a handheld. Instead of a system which can play CD-quality audio through decent speakers, you have a handheld which is underpowered in the audio department. Instead of five fret buttons which allow for several levels of complexity, you get four buttons. Instead of a game with 50-60 songs, you get...20 songs? And, oh, they also not only are keeping around the annoying-as-fuck boss battle thing from GH3, but they are making it worse by making you do stupid shit like blowing on your system? And reducing how portable your DS is by making you carry around another piece of equipment? (I'm not saying the last one is necessarily real, but then again, half of GAF thinks that the PSP's gargantuan size makes it completely non-portable when compared to a DS, so obviously those folks must be upset here...right?)
Look, music/rhythm games are awesome, and I'm all for them. DS already has EBA/Ouendan, and you would think that games that played something like Frequency or Amplitude would work great on a DS as well. PSP has some awesome ones as well -- DJ Max Portable, Gitaroo Man, etc. The thing which pisses me off here is that this game has the NAME of Guitar Hero, but absolutely none of what made Guitar Hero such a successful franchise.