The nohari window is a useful tool, if you can get your friends to actually participate with it. I have my nohari window here - only 7 people filled it out, and 2 of them used symbols instead of names, so that I could not identify them. By contrast, my johari window has 13 responses, and only 1 that I am unable to positively identify.

People in general seem much more willing to speak the positives about someone, when they know that person will see their opinions. I had several people tell me they just could not fill out the nohari window, that the descriptors were too harsh and hardline.