Pros
It's a young company that hires mostly young people in their 20s, so it's really easy to connect with the people around you. There's always something happening in the office almost every day, whether it's making ice cream to playing dodgeball--every day is a surprise. The editorial department has a tendency to operate on a different wavelength than the rest of the company since we're not focused on sales, so it's definitely more of a lax atmosphere. It's also different because it's certainly the smartest department in the company--all of your co-workers attended Top 30 colleges and half of them hold journalism degrees from Columbia. So, it's a funny, fun-loving group with whom you can interact on a more-intellectual level when you're through writing. There's a Groupon gym that you can use if you want, and there are tons of child-like break-rooms located throughout our offices, so that's always cool. Managing editors are generally nice and respected, and they have a tendency to invite you out to drinks after work or parachuting off buildings (seriously--this company is a surprise). Because of the intellectual environment, there's a lot of opportunity to improve your writing and have your co-workers and bosses help you along the way. Before you get a job offer, writers have to go through Groupon Academy so you learn to write in Groupon's style and tone.
Cons
Honestly, there aren't that many downsides if you're part of the editorial staff. A lot of the stress and pressure is placed on sales. My reason for leaving was morally-motivated in that I wanted to work for a company whose initial mission involved helping local businesses promote growth within their communities. The reality of the matter is this: Groupon has grown too fast and continues to grow fast because it's too focused on attaining (but not retaining) business clients. A majority of the profits made from deals are consumed by the company instead of the local partner with which they're working, and there's no certainty or any sort of plan to help business growth once deals expire.