Basically, Yayo was always the goonish counter-point to 50's balance between him and the lyrical robotic no-personality approach of Lloyd Banks. For me as an occasional fan of Yayo, his advantage has always been his ignorance. There was one song of the mixtapes a year or two ago, where he rapped "That's a fucked up way to die. That's a fucked up way to die. Now you're dead." Hilarious.
But that said, his material under his solo-work has been increasing more and more in quality. I think because he knows he's not a commercially viable artist, he doesn't need to try and compete in a commercial rapper sense a la Banks/50, so he's remodeling himself into a sort of champion of grimy/dark NYC vibes. And it's good on him, especially when paired with more energetic characters like Brown or Uncle Murda. He's also kind of a genius for putting Lil' B on his shit and embracing the guy so openly, because it shows he's more in touch with what's going on than say 50.