I really love my Calphalon cookware. I got the tri-ply stainless kind, one piece at a time from Amazon and ebay. I also have a couple of pieces of All-Clad. IMO, they perform equally well so it's whatever's on sale. I have a set of ss RevereWare at my place at the coast, which is equally heavy but much less expensive.
Here's the difference I can tell. The Calphalon (and All-Clad) has an aluminum core sandwiched in between 2 layers of ss, and it goes all the way up the sides, I think. The RevereWare has a separate, flat disk of aluminum between ss that is only on the bottom of the pan. Since aluminum is an excellent heat conductor, you are supposed to get more even heating, no hot spots, and the easy care of ss on the exposed surfaces.
They all warn you not to put a hot pan into cold water, as you risk the layers warping or separating. They also tell you not to use a high heat setting or separation can occur. Well, this happened on one of the RevereWare pans almost immediately so I guess I got the heat too high, although I've since read it is a common occurrence in less expensive cookware with the encapsulated disc bottoms.
The Calphalon, on the other hand, performs beautifully, is very easy to maintain, and I've had no warping or separating even though I have high capacity burners on my gas stove here. The handles don't get hot except if I put the pan in the oven. The sides have a flared lip for easy pouring straight from the pan and the glass lids fit snugly and allow for watching the food without lifting the lid.
So I'd have to say that from my experience, Calphalon has been far superior to any of my old, lesser quality cookware. That said, I personally would not pay retail or buy a "set" because it's relatively easy to pick up one piece at a time on sale at a reasonable price. I have heard that Sam's has a Member's Mark line of cookware that is virtually identical to Calphalon and All-Clad that they sell in sets at a very good price. If I hadn't already bought my cookware, I would definitely check this out because I don't care about the name and I think, like sewing machines, many finer brands are actually made in the same factory anyway.