Just reviewed the new one for a magazine. I find the more I listen to his newer stuff the more I get out of and like it. It retroactively made me like 'To Pimp...' a lot more, too.
Don't really get the coke-addled thing? I guess you mean it was self-indulgent. From what I gather he's actually more teetotal than anything.
There's this weird friction in his music between musicality (I'm sleep-deprived so can't think of a better word... 'tunefulness' perhaps?

) and his this extremely cerebral quality. At its best it smuggles this complexity under the radar, cloaked in catchy melodies.
On the whole I prefer his earlier stuff, 'Overly Dedicated' especially ('Opposites Attract', 'Average Joe'...), but I'm glad he's evolved like this, he doesn't really sound like anyone else by this point... He does have a righteous persona, perhaps, but that's rather refreshing when compared to the majority of rappers, with their wilfully ignorant personas. (Many of whom I love, natch.)
Though a very different artist, in many ways he reminds me of Eminem (including the histrionics). He's so talented at 'just' rapping that you get the sense that he's bored of it, Hence all the weird voices, multiple perspectives, dense, often cluttered production.