Personally, this was a brilliant move on Apple's part. The iMessage app is probably the most used feature on the iPhone all alone.
I can say with a certainty that in my circles (Los Angeles, entertainment industry, family, friends etc) the opening up of the messages app will be a huge "sticky" feature that will further addict users to their iPhones.
Was a bit dumbfounded yesterday reading some comments around the web like "how un-apple the changes to iMessage were" or the frequent "steve jobs is rolling over in this..." or "steve jobs would never have...."
BS!
Messaging IS the future. Clearly those bashing the changes have no clue how intensely important this one phone feature is across EVERY SINGLE DEMOGRAPHIC globally. Bewildered why anyone would underestimate the importance of better effects, emoji's, interactivity, input of video, photos, music etc into iMessage, then setting up it being offered on Android etc.
The second most important feature on an iPhone is.....
The Camera. Clearly too when iPhone 7 is released we will see that improve significantly. Those already bashing the "underwhelmed sense from no physical changes" to iPhone 7 is already a "pre disappointment" I think when all is said and done will see significant changes to the camera, to touch ID (setting up for it's complete removal as button in 2017), our audio experiences and headphones etc.
Just the headphones alone for a guy like me that NEVER has been able to use the earbuds will be a HUGE new feature if in fact they upgrade them to wireless and hopefully a better more universal fit.