Yeah, he did become more serious, yet also stayed calm and level-headed, which only further backs up my point, since even when he gets angry, he still manages to not let his emotions take total control of him. Most other shounen characters in his position would just go bereserk if they got angry like he did in the recent chapters of HXH (well, the last few before the hiatus anyways, since they aren't so recent anymore ).
Yeah, it figures that the good/entertaining and creative shounen don't last as long as they should due to a lack of popularity, yet millions of volumes get sold for something and cliche, generic, and boring as the shounen that just follow the most simple and overused formulas.