Pros
Company trips and social gatherings. If you make enough money the HR girls will try to date you, that's how you know you've made it.
Cons
IMC is a bit of a black hole. People get sucked in and lose all connection to reality. IMC tries to build a family dynamic with a casual fun work environment. You are surrounded by exceptionally bright people and it becomes a really competitive environment. Most people who begin at IMC are straight out of school, and lack any previous knowledge of working in an office environment or office politics. This makes for some highly inappropriate office relationships, favoritism from managers and generally poor feedback loops. If you are not one of the chosen favorites, you can pretty much guarantee you are not going anywhere in the company. Once you have left, you realize you have no real-world skills from that time to apply to anywhere else outside the trading world. No other trading companies will think you are great for working at IMC, and most investment banks or other financial institutions have never even heard of IMC. It's definitely good money if you can stick it out long enough to support yourself afterwards while you find a new career, but I certainly regret staying there for longer than a few years. After having worked elsewhere for a few years now, I look back on my time there and think how stupid the crap that IMC pulls is. Some companies put the smartest guy in the room in charge, some put the best leader, IMC puts the biggest suck up. If you are in Chicago and looking for trading roles, try Jump, Optiver, DRW, one of those. I think you will be a lot happier in the long run.