Not much else is known. It's being described as a Crow-esque thriller about a circus tightrope walker who is murdered and returns as a ghost with the ability to inhabit the bodies if others in order to find his killer. Thankfully this sounds like it'll be better than "The Invisible."
Deadman first appeared in Strange Adventures #205 (in October 1967) and was created by Arnold Drake and Carmine Infantino. This is admittedly the first time I've even heard of this character, but he sounds like he has an intriguing story that could make for a great movie. Of course, without too much to go off of, it's hard to tell this early if it'll be any good, but there is one big factor that makes a difference - Guillermo del Toro. Any time he's involved on something it usually means the filmmaker attached is talented and that the source material is strong enough for a great cinematic story. I trust that's the case on this Deadman movie.