Pros
Badassery in full effect! Riot focuses on hiring amazing people to tackle sweet projects and has a philosophy of making sure people have tons of autonomy to get things done. A core management principle of Riot's is to manage by goal-setting and holding people accountable for results (the ultimate result being player happiness). Another element of Riot's winning culture is the incredible focus on hiring talented people. I came here from a large developer and publisher of top games and I have seen Riot consistently pick the very best people out of my former employer with admirable precision. A third positive is Riot's Santa Monica location. I can walk to work, then hit nearby bars with colleagues before stumbling home. It's nice to be car-free for the most part. Santa Monica is gorgeous and awesome.
Cons
Growth has outpaced company infrastructure development. Small example: "emailpocalypse" of Feb 2012 in which email was disrupted for 2-4 days during an upgrade of email server infrastructure. This was the sort of infrastructure project that larger, more stable companies pull off easily. Big example: performance review system inadequacies are going to create major headaches unless addressed very soon. Now that executive management doesn't know everybody intimately (thanks to rapid growth), a fair, transparent system that works very well will be needed so that the mass of people hired over the last 18 months gets adequate coaching and career advancement.