I strongly feel a straight answer is the best answer. We, recruiters, sometimes forget that candidates will take the news a lot harder than we will. Give them as much information as you possibly can. I am not a fan of the generic answers as it leaves the candidate with possibly a bad taste in their mouth about you and/or other recruiters.
Anything that can help the job seeker, I'm all for. Especially if, perhaps I didn't do a good job in my recruiting if the client came back with just 'meh'.