So I lied...not really 100 reasons
Coppers big advantage over anything else out there is that it is an excellent heat conductor and less prone to hot spots which cause scorching problems. This heat conductivity is better than even a commercial grade aluminum...which I have a ton of as its so much more affordable. More on the shopping later.
Old School tin lined has one big drawback to it. Its only temporary and you do need to get it retinned every so often and that isn't too cheap. Not something you want to do especially if its a frequently used pan. Another drawback is that the tinned variety isn't always that thick so you do develop hot spots. Copper as in any other pot or pan the thicker it is the better it will be at even heating and avoiding hot spots.
Keeping the exterior clean isn't that hard. Twinkle copper cleaner that my Mom used on her copper bottomed Revere ware when I was a kid is cheap and effective. Surfas in Culver City stocks a copper cleaner that costs more but is in a larger quantity that is as easy to use. An old home cleaning trick is to make cut a lemon in half, dip the cut edge in salt and scrub away to bring back the shine! (I don't recommend as its a waste of a perfectly good lemon and is labor intensive).
Cooking with copper, especially the stainless steel line is a breeze. It heats fast and evenly. Perfect for candy making, caramels and syrups that are so easy to scorch, but not with copper. The steel lined interior doesn't pick up funky metallic tastes when you deglaze with acids like wine, vinegar or citrus juices can.
Buying copper, I've found some incredible deals out there. I picked up mine in bits in pieces from a variety of places. Check out Marshalls, TJ Maxx and Tuesday Morning for close outs. I even scored on some really nice speciality pieces at E. Dehillerin in Paris, yes I was there as Ina Garten and Paula Deen both featured the place on their shows and I wasn't disappointed. Charming staff, and even with the dreadful exchange rate, I saved nearly 40% over Williams Sonoma for better quality pans.
If you want a full set, one that is totally on my wish list, not a hodge podge of pieces you need to take a close look at the Calphalon Copper, best price I've found for a nice set is $399 at Bed Bath &Beyond. Seriously, I'd donate my hodge podge for that set so if anyone feels generous hmu for a mailing address. I started my copper collection about 7 years ago, which was about 6 years before the Calphalon set hit the market. Its really good stuff, copper exterior, aluminum core and a stainless steel interior. Hits all the marks to be a great set of cookware. Until them I'll just love what I have.
Copper, its what great cooks are using. Everywhere.