I applied online and heard back from HR about two weeks later via email to set up a phone interview time. We set a time for four or five days later (although it was pushed back two more days).
The phone interview was with an HR recruiter. She was extremely pleasant and easy to talk to. She asked a few questions, mostly about myself and my current job situation. There were a few specific questions aimed to get a sense of my customer service experience. Nothing was mentioned about Groupon really. The interview lasted twenty minutes. At the end, she said she wanted to go ahead and set up an in-person interview. It turned out that the next day worked for both of us, so a day later I find myself in the Groupon office.
I met with the person I interviewed with on the phone, as well as another person from HR. They interviewed me together. They asked about my current and previous work experience, education, interests, what cool things I've done, as well as a few job-specific experiences.
I then met with two customer service leads whose questions were almost all customer service related, although a few "fun" questions were thrown in too. The atmosphere was completely relaxed and fun. Informal but professional. Random questions (but all pertaining to customer service) were also drawn out of a "fishbowl." (Don't worry, the fish were all dead.)
All four people I interviewed with were absolutely awesome. They completely put my anxieties to rest and I was able to just relax and talk with four cool people. After the interviews, I had to answer a few customer service questions on a computer as if I were responding to customer questions.
Once finished I was walked out to the elevators by my original HR contact which was a very nice touch. She said I should hear from her in a week's time. The next day I got the job.
If I sound gushing, it's not because they hired me. It's because, as large and fast-growing as Groupon is, they entire time I had their undivided attention, and I was never once made to feel like they were simply trying to get me in and out the door. A++ would interview again!