Really useful! Doesn't keep up with tumblr updates nearly as fast as the older xkit(s) did, so there's a huge banner on top of my dash that I can't get rid of.. And while it's nice to have the drop down menu to toggle extensions on/off, there's not much information given about a lot of the extensions, so I never know which extension to look through when I want to block an ad/sponsored post/asktime banner/etc.