I did notice that there is a perk in the sneak tree that allows you to perform a silent roll by pressing the sprint button while sneaking. Has anyone tried using it mid combat? Is it to much of a pain to pop sneak, roll out of the way, and unsneak during a fight? Or does it only work outside of combat/when undetected?
Yes, it's useful, but it doesn't become really useful until you max out your sneak perks and get the perk that stops combat temporarily and has distant enemies look for you. You can enter sneak, roll out of the way or into a dark corner and enemies will completely lose you until you emerge behind their back and slith their throats. Simply awesome.

As for acrobatics, I miss it somewhat, I liked being able to jump high and go from rooftop to rooftop.