It's the part of the site that worked the best on mobile for me.
In fact it worked better than many hamburger menus I find on modern mobile sites.
It's not the greatest UX but it's not that bad either.
It might be because it is standard. It offloads everything to the native UI, which in many situations is a good idea. I don't know how many times I have had web pages break on mobile because of some fancy date selection widget.