Pros
I would say the main pro is that the new office allows you to work a good physical distance away from upper management who tend to be micromanagers. I also heard the many new small rooms have been great for people to cry in, as well as the bathrooms. People who drink the GLG Kool-Aid and financial goals (which are always ambiguously defined with any revenue plans resting on the shoulders of severely overworked and underpaid twenty something year olds).
Cons
If hell had a sad, bleek dungeon, that dungeon would be called GLG. This corporation does not care about its employees. I was on a team that on averaged worked 60 hours a week (on a good week). We were treated like work horses, but even worse-- we were paid an incredibly low salary and told it was "great" and normal to be working overtime. It wasn't so great to hear friends who were denied a single vacation day by managers for YEARS because "flex time off" comes with the contingency that your manager is a responsible human being and allows their hard worker employee to take a break. It wasn't so great to hear the majority of my coworkers working late nights and weekends while put under abundant amount of pressure by a boss who set teams up for failure while others were put in positions to be successful. It wasn't so great to see an entire branch of the firm receive a trip to free trip to CANCUN for doing the SAME EXACT WORK as EVERYONE ELSE in the firm while others doing the same worked watched. It wasn't equally great to know that you don't get to chose what accounts or teams you are on, which dictates your success in the firm in terms of promotions, salaries, and bonuses (I believe that's called structural inequality). The list goes on but I'll stop there.