Pros
Some people are fun to work with. You can get great experience that will help you down the line in your career.
Cons
HR is terrible here, the HR department is weak and useless and as a regular employee you don't mean much to the company(never forget that). You see people getting let go for stupid/bogus reasons. Why hire to begin with? There are many bullies and they have learned to play the game. It is very obvious HR is there to protect the management and the company. That is their goal and they will do anything. This will sound like advice to survive any corporate environment, but it's very applicable to survive at S1. Do not trust most people, especially the people that have been there for some time. Be aware of the spies, and most importantly, don't let them into your life. They practice Machiavellian principles and the "48 laws of power" to the T.