I recently took a look at the Firefox View "tab", and I could see the usefulness of a quick history list of closed tabs. However that's all it is since I don't wish to use this alongside my phone. However if this also had a drop-down for my currently open tabs and windows, to more easily visually see what I have open, I could see myself using it much more.
Currently there IS a tabs drop down on the top right-side of the window, however as a dropdown the text and icons are smaller, and you overall have less space to work with. If incorporated into Firefox View, you could remove the drop-down carrot, freeing up some of the space that the Firefox View icon takes up.
(Surprise Pro: suspect users would learn to really appreciate new tabs forming on the left instead of the right)