In my two games, Mienshao was the Pokemon I rely on the most. As Mienfoo and Mienshao it helped me out a lot. No regrets, greatest fighting weasel in Pokemon, and one of my favorite Pokemon as well.
In Black 2, as Mienfoo help me win 3 badges (forgot which ones). Evolved by 6th badge time. She took down 2 of the E4 (Marshall and Grimsley) most in 1 hit, and 5 of the 6 Pokemon of Iris (my Emolga took care of Lapras) againt, most with 1 hit. Final move set: Drain Punch, Hi Jump Kick, Aura Sphere, and Detect. Regenerator ability. As of today, she is my only level 100 Pokemon I trained from level 1 (in my White game, I breeded two Mienfoo and once the egg hatched it was a level 1). I overtrained her before E4.
In my White 2 team, I actually have 2 Mienshao, a normal male, and my shiny female. Both evolved in the same double battle. They also help me take down Drayden (for the 7th badge).