I applaud the upgrades, but maybe they should have a dry run before this goes live, as I foresee possible issues, and trying it the day of? "Interesting" is the least of my concerns.
It's quite literally just a button that adds multiple items to the cart at the same time. It doesn't have any other bearing on functionality - it'll just save people from needing to jump between product pages to add items to their cart. There shouldn't be any reason why it would cause issues for people.