Pros
Casual environment
Free tea/ coffee
Wonderful location
Cons
I interned with the editorial side of the company.
This sounds brash, but is honest: I've worked for publications where every member was a volunteer that were more organized and structured this.
I was regularly assigned tasks that were simply forgotten about and never followed up on. It was often a waste of my time.
It's almost like they signed up to have an additional, free, hand around the office but never spent the time to think about how to effectively use that person.
I was offered a letter of recommendation and had it withheld once leaving London.