Eric H.wrote a review of Zipp 303 NSW Carbon Clincher Road Wheelset on June 27, 2016
Familiarity: I've used it several times
Crosswind stability is excellent. Still get a little buffeting but quite little at 30+ mph downhill with variable strong crosswinds.
Superb dry braking. At least as good as my best aluminum rims. Better than 2015 Firesrike 404's. Excellent modulation and peak power. Huge improvement from the Firecrest 303's. Did not ride in the wet.
Weight was exactly as advertised ( a rarity in the biking equipment world...)
Aero is too subjective to comment.
Impossible to feel whether they coast better with the new hub.