Pros
I've been working for J.Crew for the past year and a half and I have to say it's been a great experience. I got hired only a few weeks after I turned 18 so it was a big privilege since most 18 year olds are still working in fast food or a supermarket. Pay wasn't bad for someone my age. The discount you get is amazing as well since the clothes are quite expensive. The environment is nice, clean cut, and a classy clientele. Clothes are really nice as well. I never wore J.Crew until I started working their and fell in love with the clothes. J.Crew is now my favorite brand.
Cons
As with all retail hours are never steady. One week you'll have 25 hours then the next week you'll have 8. Then the week after that you'll have 12 hours. You'll only get steady hours at J.Crew if you're a manager. On call shifts can be kind of annoying as well. Sometimes they'll take them when you least expect them.