Will this non Contact voltage detector be adequate for my use case?
A Non Contact Voltage Detector doesn't replace the need for a Voltmeter but it is an item I keep in my pocket as a quick verification of AC Power.  If I cut the power, I'll do a quick test before I go into a wall box to make sure it is cut.  If it indicates power when I don't expect it, I will use the volt meter at time to see what it is.  

I do get a number of false reads with the device, so if your life depends on it use a volt meter instead.  Also this is a safety tool, real cheap doesn't really sit well with me.  I'll rather spend $15 dollars at a hardware store for this from a known brand than get an unknown brand/quality.