Personally, I liked her, but I guess that it depends on what you want in a companion. Are you planning on being LS or DS?
Plan on being LS. Yeah ashara really made sin feel blah, especially after 50... At least Nadia can be thrown in something that's not a winter suit. And if her personality is even a little more mature ill be happy.
Aside from that, being rep, having stealth, and being a Jedi, shadow sounds like it will be much enjoyable.