Pros
J. Crew is one of the few retail chains that prides itself on customer service and actually means it. Employees are not forced to badger customers and are, in fact, encouraged to simply interact with them like normal people. The segue into a sale becomes much easier when the customer does not start off his or her shopping experience being annoyed. J. Crew is well known for very high-quality clothing and is a great place to work when building a wardrobe for the corporate/office world. The discount is great, and you are NOT required to wear their clothing (a rare find in the retail world). This is not to say you are not required to project their look; rather, you can wear anything that does not advertise another brand or company. I met great people working at J. Crew, as well. Commission for client specialists is great, and commission exists for sales associates (but only on sales greater than a certain amount... I think it was $150, and it's meager)
Cons
The on-call shifts are difficult, particularly if you have more than one job and need to have a more definite schedule. My on-call shifts were used some of the time, and I had them less often as a client specialist than I did as a sales associate, due to the nature of being a client specialist. It's still a major pain, though. Wear comfortable shoes because you will be on your feet on a hardwood floor for the bulk of your shift. I've never been in a J. Crew store anywhere in the country (and I've been to many) that had proper temperature regulation. You either freeze or you roast, but freezing is far preferable because J. Crew favors the layered look. People do steal sales, which matters a great deal because your performance rating is based on your sales level. As a client specialist, I had some great people who would watch out for my sales, but I was in trouble if they weren't working. When you're a sales associate it doesn't matter as much, but stealing a sale from a client specialist is a big deal because they all work on commission.