I got the Dessert Decorator Pro for Christmas a few months ago, and have been using it pretty regularly since then. It works like a charm for smooth, buttercream icings, but when I work with more cream cheese icings (or other fats), I experience a lot of pressure with it. I'll continue to use it, especially for buttercream, because the versatility and ease of use with the tips is fantastic. I am slightly disappointed, though, that if I make anything else, it becomes difficult and tiring to use (after the sixth or seventh cupcake, your hand will ache for icing).
I would recommend this for simple projects, and simple icings. But, this is by no means a professionals' tool.