Contacted by a recruiter who set me up for the interview. I did my homework on glassdoor and felt prepared for the first two interviews. Understand their business model. From here conduct a case study. I was flown into Austin and GLG was most courteous. I had 6 thirty minute interviews. I did my homework on each person I was to be interviewing with and had questions prepared for each of them. I liked all 6 of the people I met with. They were professional, hard-working, and sociable. They all ask, "tell me about GLG", "Why do you want to work here". The case review interviewer want's to see that you were resourceful with your research. The instructions are vague, I suggest going above and beyond their expectations. Impress them with your case study.
Make sure that nothing on your resume makes it look like this is a temporary job (i.e. MCAT, or LSAT scores). However, they seem very open to their company being a springboard for you so that you may one day leave for another company. They also like the idea that you potentially can stick around. My advice is to be honest about what you want. I asked many of the interviewers where they see themselves in 2-5 years, and most had no definitive vision. So if this is you, by all means, apply.
Overall it was a great experience interviewing with them. I was really looking forward to potentially working with them for a few years. I spent a good 40+ hours doing my research on GLG and even skipped out on other interview opportunities. I was sad to see that I did not get the offer.
They are looking for hardworking (not-necessarily intelligent), professionals who are unsure about a specific career path but have potential. They tend to hire recent graduates who came from a prestigious University, or had an impressive GPA. Most of all, they want someone who wants to be there. So unless you fit this bill, I wouldn't waste your time.
To be candid, there were a couple negatives about GLG: Their employees were skilled students who worked hard. Their office culture has a vibe of "work-hard, work-hard". You do not have to be intelligent to have a 4.0, you just have to work for it. I asked the interviewers what they do for fun, and most had no definition or seemed to not have given it thought in years. If you are an intelligent person who realizes the benefit of a "work-smart and play-hard" lifestyle, then you will not enjoy this aspect of the company. I would still enjoy working for them because the research role is actually challenging, and interesting.