All the phone makers trickle out the tech - they're milking the gravy train as long as they can.
The vast majority of people aren't on 1-yr upgrade cycles. They're not intending the M9 to be a major upgrade over the M8, but the M7 and people with 2+ year old phones from other OEM's.
Seems like many people barely use their phones for calls any more, so that's not a major plus for differentiation. Pretty much all you're left with is the camera, which for some reason is severely lagging possibly even battery tech.
The Samsung Edge is unique, I'll give them that. But I still think it's largely a gimmick niche product with no practical functional appllication - for all intents and purposes all they've really done is bend the edges of the screen and dictate you put apps and shortcuts there....which seems pretty restrictive for something that's supposed to be cutting edge tech.
About the only thing interesting to come to me is reduced bezel around the displays and possibly expandable displays.