You are biking around, something goes wrong, you need a quick and cheap fix without much complicating ... this is the place.
But being quick, nice and cheap comes with a price - sometimes they get overbooked and if you have something "special" to fix - it might take more time than you expected ... But they WILL get it done. Also, if you have a rare old bike, they will go that extra mile to find the necessary original parts for you, while other bicycle merchants in town just simply say "we don't do old bikes, we only want to sell new ones".