the reason the seal was uneven is cause orochimaru made it that way in fear of what Naruto could become, thankfully jiraiya undid it

come on, you guys are totally not giving credit where credit is deserved, Naruto is more than just the average joe, even without the kyubi.

plus, remember in the episode where naruto has defeating neji, and all the jounins are saying that its amazing he can control the fox demons power without losing control, THATS WHY HE IS AMAZING, he has to have determination and alot of strength on his own to be able to handle that, so there...lol