IMO it is a mistake for them to wait till E3 to have a proper reveal. That works with established IPs. I don't think it works for a new IP that releases in the fall against the big dogs. This time of year they had the whole core gaming world watching. They should of really taken advantage to get the game on our buy lists. Instead they risk being lost in the mosh pit of E3 against established games.
Well, they did have a proper reveal last year at E3 that generated a ton of buzz. Granted, no gameplay was shown but they still managed to get a lot of people excited to hear and see more about the game. I suspect that if they have a stage demo at E3 they'll once again have gamer's attention and also mainstream news organizations that cover E3.
Not only will they probably get all the publicity they need but I think gamers are hungry for a new IP for their new consoles. I think The Order will do just fine if their plan is to wait until E3 to show more of their new game.