My mate bought a bike from Halfords recently. It's a Carrera and it was great value, the guy also spent the best part of an hour going through fit, bolting on his child carrier etc. I checked all the work (obviously) and it was spot on.
It's all pot luck really, whether a store is an independent or part of a chain. There are several independent bicycle stores near me and a Halfords, but I wouldn't trust any of them to do a better job fixing or setting up a bicycle than myself.
Recently I tried all the local stores looking to get the threads cut further down the steerer on a set of forks. I got the distinct impression that I knew more about bicycles than any of the people I spoke to.
Of the independent bicycle shops near me, two predominantly sell children's bicycles and cheap BSOs, one also sells skateboards, wetsuits and surfboards and over-priced clothes and the staff seem more concerned about their trendy haircuts than the customers. And the last shop I haven't been into since I was about 15, and I would rather boil my own head than spend any time or money in there because the guy that owns it is such a miserable, grumpy git.