Well, I guess they can't all be good features.

Focus will be the first thing I disable permanently on all my own sites. I don't like or use DFW either, frankly. Don't really see the point.

I think these types of interfaces are really designed more for people who don't use max-size browser windows. If you have other things on the screen already, in other windows, then making a window just contain what you want it to contain makes a fair amount of sense. But the truth is that these features are always displayed as screenshots or video of the browser only. A better way to sell it would be to show the whole environment that it's actually useful in.. and a max-size browser just doesn't make any sense to have DFW or Focus on. IMO.