There are many great GPS training computers (Garmin, Sunto, Polar, Timex...etc) but each at a substantial price and they are yet another piece of gear. RunTracker has all the same functionality all within your smart phone which in all probability youll be carrying for safety anyway.
Battery life can be an option but for those few long training days carry an external back-up battery (Mophie, Callpod...etc) and it is a fairly comprehensive tool at a fraction of the price without all the extra gear and fuss.
Add to that seamless integrtion with Training peaks software and for my needs its all 5atar.
TriShaman about Run Tracker Pro, v13