I'm undecided. I certainly want to see it. As with any book, it might provide usefully steal-able ideas. I doubt very much I would DM a campaign with ghost PCs (even non-MM ghost PCs), much less want to play in such a campaign. (Me? Play? Shurely shome mishtake?)
As for the authors, I think Monte Cook has merit but Sean Reynolds has yet to convince me. Still, I'm looking forward to it; from the little I've heard, the concept sounds intruiging.