Cumbersome to use. Not intuitive. I thought maybe I could take a few open tabs out of several and group them. Sure, but now the rest of the tabs are gone unless I also group them. Essentially if you want to group, you have to group everything into groups or you're accessing your non-grouped tabs through a little dropdown. If that's not the case, it wasn't intuitive enough to figure out otherwise or would be efficient to use.
