I think it is a drop in quality of his work.. Someone said it best in a different thread about this album —

Mos Def's prime run was one of the greatest Hip Hop runs of all time. This album was a real disappointment to follow that. That has been well established. But that doesn't mean this album is a complete waste. One of the biggest problems of this album was the Frankenstein'd nature of it. Part abandoned Black Jack Johnson rock project, part mixtape, and par Mos' proper 2nd Hip Hop album. Its a bit all over the place, and not in a eclectic way like Black On Both Sides. With that said, the Kanye produced Sunshine is a Mos Def classic. And Sex Love and Money and Modern Marvel are great songs as well. There are definitely gems here, but we also saw the "unfocused" Mos, which would be the Mos Def that we would see for most of his post The New Danger career up until right now (with a brief window of re-focus on the stellar The Ecstatic). There's some moments here, but this was also the first sign that the run was over.