Seems like a rather generic post to dig up a thread that is about 9 months old and didn't really have much in it to begin with.Generally most of the smartphones still have problems as far as the battery is concerned, that's i think the only bad thing with smartphones especially iphones.
Define your 5-6 hours on heavy usage. Playing games or even just keeping the screen activated for 5-6 hours at a time will hurt even the 6+.
By heavy usage, I mean basic tasks but with brightness up to 90-100%...so some safari browsing, YouTube videos etc. I don't play games on my phone. Even with these basic tasks I only get about 5 hours of usage. Ibackupbot says I have 3000mah so I guess battery is not defective