I'm not a fan of radical honesty. It seems to imply that unless you are blunt and don't give a crap about the other person's feelings, you can never be "truly honest" or whatever. It just seems like an excuse to hurt people for the most part - you can tell the truth without hurting people, people do it all the time. I don't see the purpose in saying everything you think either - there are some things I think that may be negative towards a person, but I know it's due to my own prejudice (for example, I might see an outfit and think it's ugly, but that's because my own fashion sense is different). If I tell them, all I'm doing is hurting them with no purpose. I don't want them to change on my account, and I'm aware that the problem is with me, not them. What purpose would it serve to tell them that I think their outfit is ugly if I'm not asking them to change it, I don't think they're doing anything wrong, and it will have no positive effects whatsoever?
I guess writing this out I clarified my thoughts on this: I don't think honesty itself is a virtue. Sometimes it's a good thing and hurts people, but that's because the good of another result (maybe causing them to change) is greater than the bad of hurting them. Honesty itself is neither good nor bad to me.