If you use Twitter, you’d have noticed that the ‘quote’ tweet button is entirely useless. It adds the entire tweet of the person in your tweet with their handle and quotation marks, which often leaves no space to add your own comment to it, in which case you’d rather just use the retweet button.
A better way to quote someone then was to add a link to their tweet with your comment, which is precisely how the new quote button works now. It lets you type your comment with the URL of the quoted tweet automatically added to the tweet. The URL cuts into some of the 140 characters but it’s not as bad as having the entire contents of the tweet using up the space.
This, coupled with the new Twitter design change that shows linked tweets directly on the timeline in a box without having to click the link (only on official apps and website) means the quote functionality is now finally useful.