My familiarity with the Mazinger franchise only comes from the Super Robot Wars games and the Mazinkaiser OVAs, but in my opinion the director, Imagawa, is up to the task and his presence increases my interest in this project.
He did a splendid job re-imagining classic properties with Giant Robo even while respecting their traditional retro designs, so I'm fine with that at least on principle.
Naturally, there's also the fact he directed G Gundam, which is awesome enough if not very Gundam-esque on the surface, and while I haven't seen his version of Tetsujin-28...I've heard it's pretty good if not particularly innovative.
I think things should be good on the action front, if the staff is given enough of an animation budget, but with some additional luck and creative freedom this new Mazinger could be able to give the characters a certain amount of depth. Nothing outstanding, perhaps expecting this to be another Giant Robo in each and every way would be premature, just a bit more compelling than the usual formula for Super Robot shows.