Pros
Jonathan Simkhai has great people, amazing clothing, and a highly creative environment. The brand is small so you get the chance to do many different things, and collaborate with departments and people you normally would not get to if you worked at a corporate company. You will learn more here than at most places, and management is very supportive in your goals and learning objectives. Also, everyone's opinion matters at the company, it is refreshing to know your perspective counts. Other great things are 1/2 day summer Fridays, a generous clothing allowance, and really fun parties.
Cons
You work somewhat long hours, a typical day at JS for many people goes from 9-7. No one judges you for leaving on time but everyone at the brand has a great responsibility and sometimes that responsibility requires you to stay past 6pm. Don't work here if you are looking for an easy, corporate life; this brand is for people who are hungry to learn and be creative! Even though sometimes you work late, if you need to leave early it isn't a problem and I felt like the time balanced itself out.