I\'ve been pondering over this question for a while now...
On the one hand, Interface Builder offers a really easy way to design the interface and wire the elements
Using builders frees you of code that you would otherwise need to maintain and the less you need to maintain the better.
The layouts built by IB do require some maintenance but it is a standard tool with its own documentation and its own online support (forums, lists, etc). If someone else ever needs to jump into your code, you can virtually guarantee they have experience with IB, but not necessarily your particular style of layout building.