4 critical qualities:
It needs to be compelling to capture customers interest and draw them in
It needs to be personal so it understands who your customer is, where they are and what they like and it needs to remember them when they come back each time.
It needs to be useful so people can get things done faster wherever they are and move to the next big thing. It needs to combine the compelling and personal aspects to take something as dull as completing and signing a form and make it a simple, seamless experience that can be completed wherever they are
And finally, it needs to be everywhere so your customers can be reached instantly no matter what they are doing