The answer is complicated. Yes, they provide better traction and support than an all season tire. At the same time, the tread does not hold up as well as an all season during the hotter months. While the world is ablaze with the great invention of the all weather tire, we are not so won over. While they do provide better grip and traction, we've found that they don't live up to the hype.
The softer tread that lends to increased traction is exactly what makes these tires undesirable to us. As far as we're concerned, you might as well buy all weathers and used them as winters. The entire purpose of an all season tire is to provide year-round traction. If your all weather tires are running down twice as fast, you might as well keep two sets of tires for changing over or forget them all together.
We say, if you're buying new, all weather tires really aren't worth the price.