Well, for one, most of it looks ugly when it's new and looks ugly when it's old. And it splinters like crazy after a couple of years, especially if you don't water-seal it every year. This decking is a dark reddish color with a tight grain, minimal knots, and, when treated with a product like Penofin oil, it looks like teak. Another product that works well is Port Orford cedar. This wood turns a beautiful silver gray when left to weather naturally.
Redwood is a top choice on the West Coast because it is rot resistant and weathers beautifully.
You will pay more in the short term for Philippine mahogany, Port Orford cedar, vertical grain fir, or redwood than you will for pressure treated wood. However, in the long run, they are each a superior choice because they will look wonderful and weather far better, with proper maintenance, than pressure treated decking ever will. All-plastic decking materials are available, as well as composite wood products. They hold up well but still look like plastic. Explore the options available in your area, and ask questions of your contractor to determine the best choice for you.