Jay Leno test drives the 2014 IS350 -
Couple of quotes:
"It feels very German in its handling"
"It doesn't lean, it doesn't roll. Nothing flexes."
He made a couple of references to how rigid the overall chassis feels and how that gives the car a lot of stability at the limit.
Overall it sounds like he's comparing
it favorably to the 3 series but not necessarily saying it's better than the 3 series, but the 2014 IS certainly seems to be a step up from the previous generation IS (both of them) in terms of driving dynamics.