Pros
Exposure to fashion PR You will learn how to work fast on multiple projects for many clients at once You will handle many duties and be asked to provide your own creative input (because management has none) as long as it adheres to the client's aesthetic in a larger company you might only have a small part in the process so this could potentially be a good way to handle more responsibilities
Cons
You might be put in an awkward position of doing higher level work on a low level with no compensation You will not be allowed to collaborate with the other design interns or any interns for that matter Terrible and unethical creative management. Account Managers and publicists are the only ones with values. Slight exploitation of designers, you will not be paid a cent and you will do the work of senior designer alone. You will not be hired at the end of the internship and this could potentially hurt your career. Be sure to have a job lined up before your internship ends. This company doesn't hire, or pay designers so beware. I would advise designers to look elsewhere unless you want to be taken advantage of.