so how do you guys use it? i really have no idea other than one of the skills using adrenaline to cast signs.

what other things i can use with it?

Bump. I'm interested in this too. I've kind of ignored it for the most part, but I recall a benefit in The Witcher 2 when the adrenaline bar was full. What is there in TW3?

Just having it should add a small multiplier to damage. Isn't it?

Basically, adrenaline goes up with each successful attack, and goes down when not attacking. Some skills, like Flood of Anger, Undying, Whirl etc. are powered by adrenaline, so you need to keep attacking to power those attacks. In a nutshell.

As far as I know each adrenalien point (up to 3) gives +10% weapon damage.

Try checking the tutorial info menu, there (every?) game mechanic can be read.

Can confirm above posts to be true.

I can't see the adrenaline points. I only seem to lose them as I attack.

Thanks for the info guys, much appreciated!

There is also a skill that lets you consume three points of adrenaline to instantly cast a fully upgraded sign of your choice, with increased intensity. It's on the swordman's tree.

Skill to increase damage (further?) and sign intensity (if it doesn't increase damage more than adrenaline does already then it adds intensity for signs at least... 30% at 3 points? probably)
Skill to heal when health drops to 0 (saves my ass all the time when fighting much higher level monsters or humans)
There is a skill that adds 1 point automatically when you enter combat, and skills that reduce the amount of adrenaline you LOSE when you get hit up to 100%. With the healing skill, these 3 are pretty badass.

I am using the Ursine blades right now (+adrenaline generation), with +adrenaline runestones on them also, I gain adrenaline pretty quickly and enjoy the added damage bonus. I cast signs with it when needed and have the healing skill equipped as well as the skill which prevents adrenaline loss on hit. There is also a potion that adds greater adrenaline generation but I hardly feel the need for it.

Its a great resource if you specced for it, but I have not tried the other, non sword based specs yet.