We spent five days at Copper in January 08 and had a great time. The trail ratings were hard to figure out as some blues were really steep (for a blue) and some double blacks were pretty tame. Overall they have a great range of terrain, and good snow conditions. If you are a confident skier don't let the double black markers scare you off. There are many great black and double black trails that any advanced intermediate skier can conquer.
If you are from lower altitudes keep in mind that the base lodge of Copper is around 9,800 ft elevation and the summit is above 12,300 ft so you may have trouble with the altitude. To minimize the altitude sickness make sure you are in good shape before you come, drink a gallon of water each day, and avoid caffeine and alcohol.