I believe that there may be some misinterpretation of the final fight, and this applies to both characters. This final fight had both characters fighting true to their characterization throughout the entire manga.
Let us consider two things. One of them is the characters fighting style. Naruto and Sasuke have two different styles, and it was shown in the fight perfectly. First lets analyze Sasuke. Many believe that he was not holding back, but that is incorrect. Sasuke has ALWAYS fought in a gearshift-like way. His style can be summed up with "I will fight you with the least amount of ability it might take to defeat you, and if that doesn't work I will shift the gear up until you are beaten." I ask the forum, has there ever been a fight where Sasuke has fought with every of his (then current) abilities from the beginning? The answer is no.
Naruto's on the other hand has two styles. One of them is "I will lead you around until you make the one mistake that I can take advantage of to deliver one decisive blow." The other is "I will engage you with the best of my abilities that I have at the moment, and if that does not work I will slip back to style one." This has always been his way of fighting, and it works.
In the last fight between Naruto and Sasuke, Sasuke's mindset was that he wanted to kill Naruto, but he fought as he always has. That is to say his mindset was "I will kill you with the least amount of ability that it takes to kill you. If you die to a chidori/enton that would be great, but if not I will just shift up to a stronger attack." Naruto' mindset was "I will not kill you, but I have to fight with all I have to not be killed by you in turn." In other words, Naruto's not dying to weak attacks forced Sasuke to use his ALL, and Sasuke's all forced Naruto to use his ALL for the sake of not dying. They held back in the beginning but forced each other into a state of not holding back at all.
As for the much disputed bijuu-infused susanoo vs ashura kyuubi, there was not so much a stalemate in as much as Sasuke losing to his hubris and Naruto forcing the best case scenario for himself because of it. The attacks can be likened to a missile going head to head against two grenades. A missile might be stronger by itself, but it still works under the principle of detonate on whatever it hits. Naruto lobbed two VERY powerful grenades at the missile, making it detonate itself and the grenades, and that blast knocked both Naruto and Sasuke out of the sky. Best case scenario for Naruto, worst for Sasuke, and it was his own fault. It can be argued that Sasuke had more of the bijuu chakra, thus Naruto's surviving makes him stronger, but no. The kyuubi was already shown to be even to more than half of the other bijuu in chakra strength, and if natural energy makes Naruto fight on par with the kyuubi (remember their battle in the seal) then natural energy+half kyuubi just about equals all of the bijuu together. It was a good ploy on his part. And it was not Sasuke shooting bijuu chakra at Naruto. There was something interestingly and purposefully done when Kishimoto sensei made the bijuu. They all, together, have ALL of the basic chakra nature EXCEPT lightning. Curiously, Indra's arrow was lightning, which means Sasuke used their chakra as a battery and converted it into HIS lightning nature.
In the end it was a fight to show that no matter what each combatant thought or how they fought, they would equal each other because of their own individual flaws, techniques, fighting styles, etc. The outcome makes perfect sense.
What do you think?
