Game seems to be pretty short if i look at howlongtobeat and how long people need for main story + extras considering that this is an open world game but it is still much longer as GZ and also not shorter than at least other non open world singleplayer games.
I would say that this is next gen for you but Infamous 2 had pretty much the same stats on that site so that it seems normal for an Infamous game.
I think it should be bigger but it is still nothing really bad and much better as GZ if I can believe what most say about that.