Yep, that is QRP transceiver. (QRP in the ham community is transmitting with less than 5 watts.) I have a few friends that have built these kits, and I have all the parts to do it, but haven't made the time. But to answer your question, I usually use ham equipment that has the same output as this radio and the same frequencies. And yes it can be useful. I've been backpacking before using a radio kinda like that one, with a power output of around 300 mW (1/3 of a watt) and held a nice conversation (on morse code) with a fellow in Chile from a beautiful mountain peak in Colorado. When the conditions are right, the receiving station can not tell if you are running milliwatts or hundreds of watts.
If you need more info, just do a search for QRP with your favorite search engine, and you'll have mucho info.
--Chris
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He who sits still in a house all the time may be the greatest vagrant of all... Thoreau