Brisket takes a while. It's not just getting the meat warm enough to be done, but giving the collagen (protein that makes meat tough) enough time at 190°F to dissolve. So go low (200°-225°) and slow (10-12 hr). Monitor the internal temperature. When it hits 200, take it out, wrap it and put it in a cooler (room temp) for 2 hr. That does two things, the insulating effect of the wrap and the cooler gives that collagen time to dissolve, and it gives the juices time to reabsorb and make the meat juicy. Putting it in the cooler also reduces the smell in the area and makes it a bit easier to resist cutting into it too early.
BTW, if you use a pickled brisket (i.e. corned beef) you get pastrami.