Chris S wrote a review of Zipp 60 Carbon Road Wheel - Clincher on May 20, 2014
Familiarity: I've put it through the wringer
This is Zipp's entry-level carbon wheelset, but it isn't wholly comparable to the pricier and more refined Firecrest wheels because of the aluminum braking surfaces. Since I have a lot of steep descents in my area, I like these because they offer more assured braking than a 100% carbon wheel. But the Firecrest represents the most aero wheels in the Zipp line--these are one generation removed from the best in that respect so if you're looking to squeeze every possible bit of speed from your wheels you may want to keep looking. That doesn't mean that these wheels are bad, though. But neither are they cutting edge.
These wheels, or any deep carbon wheel, won't make you hugely faster. If you're a commuter simply interested in speed then it will be hard to justify the cost. But if you're a racer then you're at a competitive disadvantage to those who use deeper section carbon wheels. How many watts of energy you save is difficult to estimate because it varies based on wind angle and speed (plus Zipp doesn't have aero data for these wheels up). If the Zipp 60s save you 10 watts, and I'd be thrilled if they did, that's a negligible amount of mph at race speed. But 10 watts is a HUGE difference in effort, especially if you're already going all out, and if you can make someone work 10 watts harder just to keep you from riding off then that might be just enough to push them past their limits. That's where these wheels matter. As for weight, these wheels aren't the lightest but they are comparable to similar offerings by, say, Campagnolo. I have no problem taking Strava KOMs hammering up steep climbs with these. You'll only lose time on really long climbs at 7% or more, like the Alpe d'Huez. Only then does wheel weight matter, and it's a pretty modest effect. But the aero benefit matters at practically every other time.