Alta is by far the best skiing experience I've ever had. Although I live in North Carolina, I'm fortunate to have good friends and family in Oregon, Lake Tahoe, and Gunnison CO. In addition to the ski areas near my friends and family I've skied Whistler and the major resorts in Colorado, Wyoming, and Alberta. Alta has incredible snow and great terrain. The snow stays in great shape (probably due to the snowboard restriction). Combined with affordable lift tickets and the vast array of dining/lodging and public transportation in SLC, you have a place that can't be beat.
An other reviewer whined about the lack of groomed slopes. Corduroy can be had anywhere. If you want to be challenged and have that sweet powder you dream about, go to Alta!