I've had several pieces of Calphalon One for about a year now and use them a lot. I was initially very impressed with 4 characteristics of this cookware and my opinion has not changed:

1.) Performance. Aluminum is second only to copper in heat conductivity and copper and copper has a lot of problems that anodized aluminum doesn't. It has to be lined with a nonreactive metal (stainless steel or tin) that is a poorer heat conductor than aluminum thus detracting from it's advatage over aluminum, it requires considerable effort to keep looking good, and the cost is much greater than aluminum. The Calphalon One performs great. Heat distribution is even and fast, it makes a great fond (better than stainless steel), and I believe they have solved the reactivity-to-acidic-foods problem with their new adodizing process. I've cooked a lot of acidic foods in the chef's pan for long periods of time (several hours) and so far have experienced no "de-anodization".

2.) Design. The new handles (including the cover handles) are ergonomic, they really do stay cool, and I love the way they look. The lips on the pans are turned over slightly which makes it easier to pour from them.

3.) Ease of cleaning. This stuff is easier to keep really clean than any cookware I've used (All-Clad, old Calphalon, Sitram Cybernox, etc.). For most things a blue scrubber will do and for anything tougher a little BarKeepers Friend and a green scubber will take care of it in a few seconds. It's very easy to keep the C1 looking "like new". Anodized aluminum is MUCH harder than stainless steel so green scrubbers don't put the micro-scratches on the surface.

4.) Appearance. I love the way this stuff looks.

I highly recommend C1 but I would be interested to hear others experiences and comments.