We had to dig some holes for a deck and splashed out on this. It cost a bit but meant the hole digging took less than 30mins and was easy to get deep.
I have only used it a couple of times it meant i was able to dig the holes for our deck in 20mins instead of a couple of days. It has now be used quite a bit through this site and still going strong.
Prior to hiring you might think about whether you need to phone/email 'dial before you dig' and what size auger you need - I have 100,150, 200, 250 and 300mm ~800 long + a 300mm extension. Most people have had great success with digging their holes. If you hit a rock or a root, you need to stop and dig them out, and if it has been dry for an extended time the going can be slow, so I recommend digging a pilot hole with the 100mm filling with water, sipping a cuppa and then having a go with a larger auger. You might also find some instructive videos on youtube.