Peter is not full up on flashy powers. What could he have used? Powers he knows of include: Telepathy, regeneration, teleportation/time manipulation, flight, painting the future, locating, invisibility, super-strength and telekinesis. We can't count Ted's power since he obviouisly wouldn't use that. None of these powers are really flashy to begin with. He used super-strength on Sylar and that was enough really. Even if NBC ponied up some money for special effects, it wouldn't have made much difference in this fight.
And people shouldn't be disppointed with this standoff. Be glad we saw what we did. The show has covered up the violence from the very beginning. We never once saw Jessica tear people in half. We didn't see Sylar kill anyone of his victims until Jackie. And even then, it was just a little line of blood. Same thing happened with Charlie. Most of the time, all we see is dead bodies (the Walkers, Dale, Zane, Eden, etc.) because if god forbid we see people killing other innocent or good characters, parents who don't care enough to monitor their children's tv viewing would complain more than those who are complaining about the finale. Regardless, Peter and Sylar aren't exactly trained fighters. I doubt either of them could last in a fight longer than ten minutes, even if they used their powers. Plus it would be boring after about one tk blast.
In Suresh's apartment, Sylar chokes Peter, Peter flings him back. Any more tk exchange between the two of them would have sucked. So short of teleporting away, leaving Mohinder to die, what could Peter have done? Paint a pretty picture? He turns invisible. The glass thing made the use of tk again cool. And Sylar did it as soon as Peter turned invisible. So Peter couldn't attack Sylar w/o giving himself away. Hence, end of fight when Sylar flings the glass out suddenly.
The last fight begins the same, w/ Peter held up by tk. Sylar doesn't let Bennet or Parkman break his hold on Peter this time. Not that the use of guns could've added to the fight anymore than they did. He grabs a parking meter. Also a good use of tk. Using tk to bring yourself weapons is always much better on screen than just flinging your enemy away. Jessica comes in. Her power isn't flashy either. Peter punches him a bunch, and the fight ends since he starts glowing. Why didn't Sylar use his other powers? He wanted to stop Peter from going nuclear, but only after it was obvious to everyone else that he was the bomb. He wanted to be the hero. If he just killed Peter outright, we'd still think he was a badguy. If everybody sees Peter about to go boom, then Sylar kills him, Sylar = Hero. That's why Syalr didn't just snap Peter's neck with tk.
The point is, everybody, that flashy special effects aren't necessary to make the fight interesting or sensical. Many of the powers only come with inexpensive sound effects anyway (i.e. telepathy, persuasion, super-hearing, locating, technokinesis, super-strength, memory). I can't imagine that people are this upset about not seeing Peter disappear again (invisibility/teleportation) or be pulled around by a rope (flight/tk) or having a few ripples around him (phasing) or heal from death yet again. Stop complaining about there not being enough special effects in fight scenes. Or about fight scenes being too short. You people are hungry for graphic violence!!! Lay off, please.