I applied through my campus career center. From the first interview to the final offer, the process took 1 month and 1 day. There was a pre-interview social the night before both interviews (campus and Mega/day office with good food, good conversation.
For the campus interview, I interviewed with a senior manager. She told me about herself first, then asked me to talk about my current internship . Then she gave me the opportunity to ask questions until our time slot was up. The whole interview was extremely conversational and flowed very well. She asked me no behavioral or standard interview questions.
My interview was on a Friday and I believe I got the call the following Thursday. The interviewer herself called me to let me know I was going forward in the process.
EY paid for all candidates (even local) to stay in the W Hotel the night before the interview. We all boarded charter buses to the managing director's home about 20 minutes away. Most of the staff there were staff and seniors (around the age of most interviewers), so again conversation flowed.
The local EY office is undergoing significant renovations, so the interviews the next day were held at another fancy hotel near the office. First, we had lunch along with a presentation by a partner. I actually didn't know this beforehand, but EY Atlanta has more than half of the market share in the state of Georgia, particularly metro Atlanta. In other words, EY Atlanta holds more clients in the city than the other big four firms combined plus some. What that means to us students? Bigger clients, more opportunity, less travel to random remote locations for weeks on end, etc.
I interviewed with a manager, then a partner, then a senior manager. A big portion of each interview was again them allowing me ask them questions. There were several standard or quasi standard interview questions thrown in there but once the conversation was established, it only seemed natural for them to ask and for me to answer in a natural way. Still conversational I would say.
All the candidates and hosts went back to a main area for snacks/sweets and very, very short closing presentation. It was a Thursday and they told us we'd hear back by Tuesday. Most of us ending up hearing back a day later Wednesday.
Overall, I would say this is a relatively easy interview process, though the unexpectedness of any interview process is nerve wrecking. I used questions from glassdoor to prepare for the interview. I'll add that I applied to EY in undergrad, they didn't even select me for a campus interview. Did well in grad school once I found some motivation and I got the offer after applying again. So my advice to any undergrad accounting student who doesn't get that dream job or internship offer: pick a state grad school in a major metropolitan area with an EY, work your butt off, and try again. There's hope.