The reason the Herald remains in my middle list (aka perfectly good, not a winner or loser) is I feel the class is more a rearrangement of the paladin than a true improvement.I really feel like the Herald is a vast improvement over the old Paladin class. Maneuvers, cantrips, the various exploration and social tier abilities, and a more sensible way of handling Divine Smite all add up to a really awesome class, IMHO.
Smite abilities are mostly reflavored smite spells, many of the paladin abilities are there just now chosen from lists, and you have to give up several paladin abilities that you used to get as part of the core class. I think its a very solid class, a worthy paladin....I just don't think it brings as much new to the table as some of the winners I chose.