Note that I was interviewing as an experienced hire, rather than a new grad, even though I was interviewing for an "entry level" position. It's because I was changing industries.
The interview process was long, and quite rigorous, consisting of an email chain, a phone screen, and a full 9-hour on-site interview. I was a bit psyched out when they called the day before my on-site to warn me that it would be tough, and not to feel bad if I was sent home early for poor performance.
The phone screen consisted of some basic programming terminology and concept questions, and one big design question that took a much higher level approach. It was surprisingly insightful, inherently taught me something about the nature of the job, and was fun to answer. The interviewer was friendly, casual, but focused and presented a fair challenge. The job, even at the entry level, grooms entry level and developing employees for jobs higher up the ladder, I felt this was a good sign from my perspective.
There was also a personality test, something they use to learn more about you that has no impact on whether you're hired. I think it was called the Personality Index or something; anyway, it was interesting, and painless, and when they give you the results it's eerily accurate.
The on-site started with a big breakfast, and it was delicious. Not really important to the outcome of the interview, but was a great intro to the company culture, interview difficulty notwithstanding. Sitting down and eating with one of the other employees to chat and ease me into the process was great, whereas I've been taught the traditional wisdom is not to risk any kind of faux pas by even accepting a drink of water during an interview.
After breakfast, was the whiteboarding session, which they call a "case," and was over two hours long, all one problem. I'll describe it below since Glassdoor doesn't let you review an interview without posting a question.
After the case, I got to meet more employees and shoot the breeze with them, since I wasn't sent home early after the exhausting case. I had the chance to ask and answer questions in a very casual, friendly way. They took me to a really nice lunch where I got to chat with a manager and a senior developer about random, non-work-related stuff. After lunch, I met with the office VP for a personal interview, where I was asked the kinds of questions you would expect, about a time I had to make a hard choice, or felt underprepared for a hard task. Typical personality and history type stuff, though I felt there was a subtext and a side evaluation being done, like the questions weren't really the goal of that part of the interview. I think it was more an evaluation of my ability to stand up to pressure and scrutiny, in other words, my ability to interface with clients. Just a suspicion.
Finally, they gave me the BAPT test, which was surprisingly fun, but stressful due to time limitations. You can look it up, it's basically a programming test with a fictional language, that tests your ability to learn and apply new languages to problems quickly. That took another few hours.
At the end of the day, I was beat, and they said "if you get this job, this is how you'll feel at the end of a typical work day." I got an offer, and they were right, but to be honest I couldn't be happier because the work is fun, and I'm accomplishing and learning new things every day.