I have, and I love it! I am fortunate enough to live near Sugarcraft, and picked up a few there. They work well, and are easy to squeeze. I had tried to use some cheapies (bought mustard and ketchup bottles at Target when they were on clearance) and the plastic was so stiff it made my hand sore trying to use them.
I have both sizes, and find that the small size is best for the detail work, but the large size is handy for doing the base coat of icing, as it doesn't need to be refilled as often. I love the coupling that is on the top of the bottle, so I can use whatever decorating tip I want.
I have only used them with Antonia74's recipe for cookie icing. I don't think I'd use them for anything with shortening or butter, as it would be hard to get them clean inside. With the royal, I fill them with hot water and the icing dissolves quickly, then I empty and wash in soapy water.