I just started practicing and bought this with my first violin. I'm not goal-directed and the shoulder rest fulfills its purpose in my use.
I like this product very much, it was cheap and works like a dream. It has a very good quality-prize ratio. My friend who knows more about violins also thinks this is a good product for me.
The shoulder rest is easy to use and very stable, it doesn't slip once you have adjusted it. I learned right away how to install it to my violin. I find it comfortable and the material is nice. It's made of plastic and metal. It seems pretty durable. It's adjustable for different heights and widths so I think it fits most of people and 4/4 violins.
I honestly don't have any bad word about this product. But as a beginner, I can't say if there are flaws that more experienced violinist could recognize.
Anyways, I recommend this product to anyone who wants to start playing violin as a hobby and don't want to pay massive amounts of money.