NBCNEWS tested the service right at rush hour:
http://t.today.com/money/amazons-new...est-1D80390021
The kid delivered in 30 minutes.
Of note:
1- the app lets you track the package in more or less real time
2- recommended tip was $5
Two hour "free" delivery sounds better by the minute.
The kid may not be a Flash but that was a pretty good run.