I know a number of people who swear by Douglas J for its affordability, and the fact that the students cannot take tips.
My wife, on the other hand, got a haircut here which took the majority of 2 hours, and she was not happy with the result. It was acceptable, but not what she asked for.
As with any hair service though, your experience depends on the stylist you get, so if you are in the market for an affordable salon, choose this one.
However, if you want a consistent result, you might want to go upmarket...