Demon Days elevated Gorillaz from a gimmick band to a dance rock/hip-hop/electropop juggernaut, and "Feel Good Inc." was the biggest song from that album.
No, these commercials got the heart of what an iPod was supposed to do--let you dance to anything, anywhere, which was an unbelievably novel concept even as recently as 15 years ago.
One of the most memorable songs from those commercials was "Feel Good Inc." And that's because it compels you to dance. It's got a great beat, but is elevated from the toe-tapping territory of "19-2000" to a completely different level by the contribution of De La Soul.
First of all, the verses aren't really different from the chorus--the spaceyness of the prechorus sets up a deceptive contrast that really isn't there. But whereas it feels like 2D is being pulled through his vocal lines, De La Soul is the one doing the pulling. The result is that when De La Soul comes in, you know shit's getting serious, and by the time he breaks out the "Don't stop--get it get it" (which is one of my favorite lines in this or any song), you've already gone completely nuts.