We're pretty psyched about some of the new things 13 lets us do. Overall I think our layouts are going to be simpler--with fewer stacked objects, and fewer sliding tricks on Go now that we have resize triggers. And our layouts are becoming more responsive. Animations are a big part of that and we've posted an example file showing how one might do animated switches in 13.
It's a small thing, but adds to the joy of a solution. Part of it feeling like "real software" ;-)