Well, Shonen Sunday's main readership is 13-18; which is actually slightly higher than that of Shonen Jump. From the looks of the protagonist, it looks like it will be aimed at the lower half of that scale.
Obviously, I don't expect drugs gangs, violent Stolen and bloody violence, but even if it dealt with a few more mature themes, then it should do well. I hope it does well, so Viz Media can license it and release it (they did recently start a Shonen Sunday imprint didn't they?).