It's actually way better than bookmarks because it stores the content in a quickly accessible way (unless the tab has been unloaded manually or through another extension), and it also stores history (you can go back and forward in each of those tabs). Bookmarks and "Speed Dial" (which is available on Firefox) do not support tab history. I do not know how Opera's Speed Dial worked though.
> It's actually way better than bookmarks because it stores the content in a quickly accessible way
I am skeptical about this part. If you tag your bookmark's, it then becomes easy to look it up right from the address bar by just typing a tag name. That is actually much easier and faster than searching through 100's or 1000's of tabs.
> ... and it also stores history
That's a very good point that I hadn't considered.
