Beef is medium done when its temperature reaches 160 degrees Fahrenheit. With a smoker running at 225 degrees, it could take two hours or less for a 2 pound trimmed brisket to reach this level of doneness.
To improve the flavor, try smoking it until it reaches an internal temperature of 145 degrees. Remove it and let it rest for 20 minutes, then pop it into a 500 degree oven for 8 to 10 minutes, or just long enough to slightly brown the outer surface.
Allow it to rest again for a few minutes before slicing and serving.