Greg Sandow likes it:
The cadenza must be about eight minutes long, and involves gypsy music, whistling, tapping on the violin, music for the orchestra as well as the soloist, and a lot of joy.
The joy is one reason the whole thing works. It's excessive; that's easy to say. It goes on too long. It's self-indulgent. All of these will be common reactions. It has nothing to do with Mozart. This last thought kept going through my head, even though, moment by moment, I loved everything Apap does. (It's all a kind of silly shtick, too. I forgot that objection.)
But this thought--that the video has nothing to do with Mozart--turned out to be completely, utterly, shockingly wrong. Because when the cadenza finally ends, and Mozart's music comes back, Mozart's ending sounds astonishingly right, as if Mozart wrote it expressly to follow everything Apap has just played. I've elsewhere written (in a recent Wall Street Journal review--or maybe it hasn't appeared yet) that these concerti are essentially entertainment, and that they just about require the soloist to improvise embellishments. I didn't quite imagine the embellishments in the style(s) of Apap's cadenza, but that turns out not to be a problem. The spirit matters more than the letter, and Apap's spirit is exactly right.
"The spirit matters more than the letter, and Apap's spirit is exactly right." Of course, there's a question of degree. Some people just hate having cadenzas in another style stuck in the middle of a "Classical" piece. It's interesting that the "should he or shouldn't he" debate can never end. But the "I like or don't like" exchange can be just as interesting. And is something that evolves more than is ever settled.