Pros: terrible free coffee.
Cons: everything else.
Groupon does a great job at having a training program that feels like college all over again, they do this to hide the fact that once you get out of it there is little job security, no money to be made, and you are constantly micromanaged. You will get a few emails a day from your boss who sits right next to you to do better, then a couple G-chats asking if you can commit to doing better, then finally a meeting or two where you will be asked to do more.
The "senior" salespeople hate the job, but can't leave it because they are making easy money, the new salespeople have to grind 10 hours a day everyday to pick up the scraps of businesses no one else cared about because they won't make money.
As far as job security goes there is none, as it is cheaper to make the work environment terrible for new people so they quit, rather than actually investing in them and foster a comfortable work environment to encourage people to stay.
At Groupon there are two segments of people, people who got in before the bubble popped on making money (2 or more years) and the never ending rotation of people who quit prior to making it one year.
This job is horrible. Run.