The graphics aren't at issue - they're adequate for the task at hand. The theme is very young with a loopy little character that demonstrates the rhythmic patterns so you can follow along. Given the young theme, the game is surprisingly difficult and is more appropriate for older children or even young adults that have a year or two of music training. Perhaps that explains the subtitle of Rhythm 'n Notes, "Improve your music skills." There isn't nearly enough variety in the game and there aren't many opportunities to explore or do free play on piano-style instruments or rhythm instruments. There is no option to record or save tunes, so be aware that this isn't any kind of music creator. There aren't even play-alongs that would provide a slightly less mundane practice experience. Get used to staring at the same two or three screens for the few hours it will take you to exhaust Rhythm 'n Notes.
The biggest failing is sound and audio. Practicing or copying rhythm patterns is fine, but the tones coming out of the DS speakers create real obstacles to progress in the chord and note training. The less nuanced harmonics or overtones in computer-generated music coupled with the limited range delivered through the DS just makes for a experience. Even a trained ear will have difficulty picking out notes and differentiating between chords. There is a screen that lets you listen to each chord prior to entering the training exercise. When the three-note chord is played in the training, you have to select the correct choice from the touch-screen. You can repeat the chord and you have no initial reference note or chord. This is crazy. Are we training someone with perfect pitch? Each chord should be voiced once in its note-sequence and then as a single chord to help beginners or to create a more approachable basic exercise. You have to realize that many student musicians aren't all that comfortable determining high vs. low with notes played in sequence, so asking them to perfectly capture a three-note chord voicing without a reference is crazy. The chord/note training is really a wash. Almost nobody will enjoy it, and even if they do it is limited to a short-list of exercises that never gets into very advanced chords. The free-play and note training is opened up later rather than introduced at the beginning, which will shut down all but the more advanced musicians.