Consistently the best
Ive been using the JuneCloud Deliveries widget on OS X since 2011 and when they launched the accompanying iOS app I could not have been more thrilled.
The app has evolved slowly over time with such features as tracking number detection when one is on your clipboard, notification center widget, and most recently my favorite addition: a map with tracking lines of the journey a package has taken.
Only real con that I have come across is that I find myself now scrutinizing the speed of delivery across carriers, which is pretty ridiculous given how an item can make it from a warehouse 2,000mi away to my doorstep in under a week.
_GABO_ about
Deliveries: a package tracker, v7.0.1