I also used to have a membership at Caswells...
They tend to be rather hit and miss with respect to customer service. Sometimes you can walk in and get helped immediately. Other times you'll wait till they get around to assisting you. From what I recall they also don't tend to be consistent about ammo and targets. Sometimes they will allow you to use your own ammo/targets and other times they will require you to purchase theirs. I think, however, that this is more of an issue with individuals working there.
Oh and the one thing that really disturbed me about Caswells was the lack of ventilation. It's been several years since I shot there but, at the time, the only ventilation on the range was a series of swamp coolers. I have to hope that the Fed's have intervened and forced them to improve the ventilation in the last few years. I do not, on the other hand, know if they have made any improvement to the range since my last visit.