They offer some light information about themselves, but nothing really tangible. Your questions go unanswered, you never met their friends, and you are generally in the dark not only with their past — but with their present, as well.
What to do: If they are truly interested in you, they will want to introduce you to their friends – and in time, their family as well. Sharing about their job, hobbies, and interests is more than normal. If they aren't including you in what's important to them, chances are they are just playing around.