I used to reach for Bobbi Brown's Face Blender brush a lot more before I acquired several wonderful other face brushes that do my finishing, blending and color application. Bobbi's Face blender does most of the above quite successfully and is truly a good brush. Just not as good. The Bobbi Brown website doesn't mention what kind of hair was used, but I'll go out on a limb and assume it's goat.
The brush is of medium size and density compared to other face brushes, and is soft enough to feel nice against the skin. It has some give and bounce, so it's just as good for blending and softening any lines that were left from bronzer or blush as it is for a light dusting of finishing powder and buffing it nicely. It's not the right brush if you're looking for a precise or high coverage powder application; that's where a flat-top brush can serve you better. I also prefer wider brushes for bronzing and a round head for blush. But if I were traveling and packing lightly, a multitasking brush like Bobbi's Blender would have been a good option.
Bobbi Brown Face Blender Brush ($45) is available from most department stores and bobbibrowncosmetics.com.
Photos are mine (and Sophie's). Here's a bonus photo of her tabbiness, just because: