It has to do with the way UIViewController titles now work. When you tap something that pushes a new view controller onto the stack, the current title animates left and _becomes_ the new back button. The animation is not only pretty, it makes it really obvious where you are going, and how to get back.
Not only that, but by default, swipinging the view controller off to the right I.e. Physically reversing the animation that brought in in, also functions to go back, so the 'button' is more of a signpost of what you will go back to than something that must be used as a button.
The reviews don't mention this because frankly a lot of them are superficial - or they are focused on justifying a number or a thumbs up or down rating that they have assigned, rather than helping people to understand anything.
