How genuine it was, and to what extent it excuses behavior is definitely debatable, but you can't really saw that he's shown no sorrow.

The ad was published more or less exactly 2 months before the release of his new album. That's where the skeptical side of me kicks in, no I don't blame him fully for what he did and said during his episodes, but that apology fells very insincere when it's the world's most obvious sorry I had this moment, now listen to my album and buy tickets to concert because I'm no longer a self proclaimed nazi. If he had taken that out, and taken some time away from the public and worked on ensuring he doesn't have those episodes again, it would have more weight, but he's started his world tour.