Apple's leadership in UI design the last couple of years has been a little lackluster. While they seem to be able to iterate, with a few missteps, I'm less sure about their capability to get a whole revamp done right.
The talent is surely there but the question is whether the leadership and willing to take the right risks is. It's going to be interesting going forward, I'm guessing they will have to introduce something widget/tile -ish in the next phone