Killer? Maybe not but....
The majority of the specs [if true] meet or exceed what the iPhone 6+ has.
If you look at recent Apple adds on the iPhone, they seem to be promoting the "health" features - something that was in the S5 already - and a bigger phone - something that the S4 and S5 had already. Yes they promoted a thinner phone but after you add a case/cover to protect it [from bending!] it isn't as thin as it was.
The iPhone 6 series also have been hit with numerous OS bugs and issues such as upgrades, warmth, Wi-Fi issues, etc. [Let's not forget the U2 album issue!]