Not that the timelines are never contradictory in Heroes, but if that's his dad in the samurai suit then why doesn't future dad give Hiro more credit... I mean wouldn't he know that Hiro was going to be a hero?  Well I guess we should watch and see... just something that crossed my mind. 
But I agree that the fight was somewhat anti-climactic... I would have been OK with Sylar, Parkman and the Petrellis deaths.  It would have been a brave choice to kill those guys off.  Tragic sacrifices are good payoffs.