I have mixed feelings about it. If she enjoys it, if I can see her desire as she plays with them, why not. But I won't ask for it or put on the list of things I like most. Though I would say a solid cupping or a little queeze during a bj is very pleasurable. But as "part of" the bj.
Edit:
The other day I read somewhere a member stated liking "having the power/control" over her guy during a bj. If she holds them in her hands, that's even more true I guess. Which feels nice for us too
Not really. I don't like the tickling. Plus I have a hairy chest. It's not sexy when she has to stop to spit out a hair