That surprises the hell out of me. The game was substandard. Then again famitsu keeping the top 10 filled with final fantasies and dragon quests, some of which were decent, but nothing special, says something about the tastes of the reviewers.
This was a reader's choice thing, so it's really even worse.
As for the DS Guitar Hero, it kind of just seems like they're milking the franchise. The original developers of it left after the second one and did Rock Band anyway.