Outdoor GPS vs Android (video included)

Many Android users have conclusively proven that Android can be used effectively as an outdoor GPS, substituting for an expensive handheld outdoor GPS from Garmin.

This is especially worth looking at given a new video about the threat to Garmin outdoor GPS from Android GPS apps.

Since the GPS in an Android can use satellites even without cell coverage, it can be used in remote backcountry areas. It is suggested you use apps like BackCountry Navigator that store maps for future use. 

If using your Android phone (or tablet) as an outdoor GPS in wet areas, some waterpoof protection is desired. Also, according to reports, spare smartphone batteries are becoming cheap, and are handy to take with you. 

What is your experience using an Android GPS App and can it substitute for a Garmin outdoor GPS?