I think the most useless perks are the ones for alchemy, and many of the spell related perks.

As for the rolling perk, I use it all the time. When sneaking around in an unknown area you have to sneak most of the time. Rolling just speeds it up.

Silent roll is a bad perk, but it's the best perk in the world if compared only with the lockpicking tree.

I've found it handy in closing quickly to an enemy for a stealth kill. Afterall, sneak power attack with a sword and a dagger kills almost anything, while a sneak arrow shot only tickles enemies with a pre- or suffix (with skill ~50, 3x sneak attack perk, unimproved ebony bow and elven arrows).