Over the last four years since purchasing the Wilton Dessert Decorator Pro, I have observed a number of pros and cons of the product. I cannot say which one outweighs the other, so the following is a short-list of what I've found:
1. Icing - especially those that are whipping-cream-based - will not become runny from the heat of your hands
2. You don't have to worry about having your icing bag explode on you
3. It's easy to fill, and isn't as messy to refill as an icing bag (at least, for me it was)
4. It's easy to clean (more so than an icing bag), and it won't stain like an icing bag can
1. It's difficult - if not impossible - to use it for making roses; other delicate decorations can also be harder to do
2. While a number of parts are metal (=good), other parts are plastic... which breaks. The thumb lever on mine broke the second time I used it (using the larger piston instead makes it a lot trickier to decorate); then the plastic disc, which pushes the icing down, started falling off of the metal rod that held it; then the top button (of the large piston) cracked and fell off... now I have to deal with it randomly falling off whenever I'm using the decorator, causing me to stop to place it back where it belongs; and then I noticed that both couplers have developed small cracks in them, too.
3. The price (it's too much, in my opinion, to be paying the full retail price)
I would absolutely love this product if the plastic parts didn't break on me (perhaps having them replaced with metal parts would be better), and if the metal-plastic connections (as with the piston) didn't become separated from each other.