I liked his Doyle's concept, though I am not particularly looking forward to Company, but I think what he does add to Sweeney is another character that's always been there, but is never as highlighted.
The music plays such a key role to the Sweeney Todd, and I think he's exploring how much the music is an active member of the ensemble, and that it is the impetus for all action.
Us, as Sondheim lovers, know how important, and how brilliantly written Sweeney (and the rest of his music) is, and so does Doyle, and he is making it a main character, and not just some music in which people sing over sometimes.
It didn't get in my way, in fact, I loved it, and a lot of the time, I watched the characters who weren't involved in the scene as they played, because they acted WHILE they played, specifically Tobias. And it added a lot for me, personally.
But I can understand how some think it's gimmicky, and I think it definately was on the border, but the concept worked for me.
Staging wise, I hope they cleaned it up a bit from when I saw it in previews, but otherwise I loved it.
Personally, I think I have too much bloom.