John Gruber (Daring Fireball): iPhone 6s (or whatever it’s called) will have the biggest jump in camera tech ever (perhaps dual-lens based on technology acquired from Linx)
-(http://daringfireball.net/thetalkshow/2014/11/15/ep-100)

Mark Gurman (9to5Mac): Same exterior (perhaps 0.13mm deeper, which is too small to be noticeable). Updated interior with fewer chips. Rose Gold as an option. Difference is size could be due to inclusion of Force Touch (not sure at all, just reporting feedback and comments on the article itself). Will have faster LTE (updated Qualcomm chip).
-(http://9to5mac.com/2015/07/03/iphone-6s-photos-nfc-storage-chips/)

WSJ: Apple manufacturing a record number of iPhones (90mn). Same sizes.
-(http://www.wsj.com/articles/apple-preparing-record-number-of-new-iphones-1436367371)

Will have iOS9 (master of the obvious, yours truly).