Well, you get armor, dodge and crit from it. So it has mitigation, avoid and threat covered in one package. And it scales with Kings. If you don't need Expertise then it's not that bad a deal. Just don't expect one gem to make all the difference. And I would only honor the socket bonus if it doesn't cost too much to do so. I wouldn't gem blue, red, yellow sockets just to get a 9 stam bonus.
YMMV. This heavily depends on your +hit/+exp and how comfortable you feel with what you have. I found I don't need to reach the soft caps and I'm comfortable with being a few percent below them.