Above all, a mobile phone app needs to be very usable. Users on the go do not have the luxury of a big computer screen, and a stable internet connection, so their maneuvering capabilities are severely compromised. As the problem is unsolvable at the users end, the smart phone app needs to be built to work around small screens, bad internet and lousy touch phones.
Keeping in mind all that can go wrong on the move, apps need to be light, so that they open fast and process faster, be clutter free to allow easy user maneuverability, and have great aesthetic value, to attract its target audience in the first place. Another important factor is that users on the move are fairly impatient; applications that take too long to load will be shot down by a huge percentage.