I was thinking about grabbing it for my 2-Handed warrior and was wondering how useful it is.

I was under the impression that it was bugged...Don't quote me on that.

Quick Reflexes is an amazing perk! It's one of the few that really changes gameplay. It enables you to easily dodge a blow and counter with your own! I use it with two-handed myself - it works just fine.
It also triggers on almost all creature attacks. This makes dealing with those pesky Trolls and Sabre Cats a lot easier!

Possibly one of the most OP perks in the game.

It's a very good perk. Some would say too good, but I personally think a two-handed warrior needs it. Depending on how quickly you go for it, it can really help early on in the game... against surprise attacks from Sabre Cats for instance.

Just do it

I was mostly worried about it being OP or buggy. I think I will try it out for a bit but keep a save to go back to if I do not like it or find it useless.

It is buggy. When you are fighting multiple enemies it sometimes gets stuck in slow mode until the whole fight ends. it happens too often for me.

Also this constantly slowing time is very annoying to me even when it's not bugging out. I guess my reflexes are too good for this perk.