My T gives a little of herself sometimes, and it is quite useful and helps with the therapeutic relationship and bonding or whatever. I don't know if I think of it as vulnerability though, particularly because I don't think she would talk about stuff that she hasn't fully dealt with emotionally. I think the things she shares are things intended to help me, either because I have expressed a desire to know or because she wants me to feel more connected to her (which I generally welcome). The downside is that occasionally things she shares bother me quite unexpectedly. I think it's better when she errs on the side of caution, but I don't know that I could be doing the work I'm doing if she wasn't willing/able to be herself in therapy.