The brute shot isn't exactly the cutting edge of death when it comes to medium-long range combat. However the weapon is surprisingly effective in close combat.
The small grenades the weapon fires aren't too powerful, however they can leave the enemy disoriented. In multiplayer try getting up close with the brute shot and firing a few grenades into their face. The blast should disorient them and allow you to charge in the weapons blade to finish them off. Its pretty fun, try it out.
[editors note: the most damage that a brute shot can deliver is from above, so watchout for that guy hanging out on top of buildings and natural formations]