Kind of redundant. The main search bar defaults to "this shop" anyway. I had to look at your page 3 times before I noticed the new search bar squeezed in between the featured items and listings.
Where it's really needed, and what sellers have been asking for for years, is a shop search from an item listing.
I hadn't even noticed. I'm new so I don't have many listing yet, but when I do it will be a great feature to have in my shop, especially because I make so many different items. Once I get them all listed, it will make it a lot easier to find a specific listing. Awesome!