I'm 99% sure the escape key will be there when in Terminal.app, I also imagine terminals like iTerm2 will have some really sweet TouchBar options to make it even better with all your console apps.
The feel of a real button is great, but you can imagine the possibilities of what you can do with that space when you look at your MacBook keyboard right now and notice you likely never use a thing but the escape key, brightness and volume.
I haven't used it yet, so I can't judge it too much, but I imagine Escape actually works well since it's the top corner of the keyboard and easy to feel, if escape were anywhere else it would really suck.
The only F key I don't use regularly is f6. (Though f2 is mainly a Windows thing... I doubt I use it much in OS X.)
I've got a keyboard with clicky button-type Esc and F keys, which might be a fair approximation to the new F key strip. (Pressing them isn't a million miles away from clicking on the Force Touch trackpad.)