Interface Builder encourages rapid prototyping and iteration, and I personally prefer modifying a storyboard someone else wrote than deciphering a wall of layout code that typically contains a ton of magic numbers.
Xcode's refactoring tools will handle updating the Storyboard's connections for you. Also, you can use multiple Storyboards in your app to keep things organized and simple to deal with.
A code review should be easier with Storyboards, because there should be a lot less code! A design review would be good, to make sure the view appears the way its supposed to.
Check out Apple's WWDC session from a couple of years ago where they show how they built iPhoto using storyboards. It's definitely possible to build rich UI using these tools.
