Bursts of adrenaline enhance your reflexes with a certain chance after you get hit and let you move faster for 10 seconds.
While the speed boost of Adrenaline Burst is considerable - it multiplies character speed by 2.5 -, its unpredictability makes it hard to be used very efficiently, as you should always be prepared to run around with your regular speed and shouldn't depend on it to keep your distance or run away from creatures. Also, since this bonus removes and is removed by haste spells, it won't stack with other temporary bonuses, reducing its usefulness.
Overall, it's not worth unlocking this charm before the other offensive and defensive charms. Given its low cost, however, it may be interesting in certain situations that could lead to funny unusual hunting moments.