The opposite's true. The current shape Yaris is fine for the motorway as far as small cars go. The Punto on the other hand is really isn't nice at all - noisy, unrefined, a lot of vibration going through the car, and it tends to wander.
What? The current Punto is so much nicer on the motorway than the current Yaris. I've driven both a 06 Punto Grande and 06 Yaris extensively, and I'd take the Punto anyday of the week, especially when motorway driving is involved. The Yaris feels flimsy, and the only car I've driven that feels lighter is a 500. The Punto feels fairly well planted, and whilst it doesn't have the same pull, it certainly feels safer and more comfortable.