Pros
The folks I worked with were all crazy talented. Lots of perks. Early in my stay it was an incredibly energetic workplace filled with passionate people who just wanted to create kickass content.
Cons
Teams became bloated. Still, content output dwindled as the 'horizontal' culture rested at odds with the unchecked growth. What's left is the worst of both worlds -- any of the massive number of employees can grind production to a halt if they're loud enough, so you get huge teams working in bubbles -- distant enough to make maintaining visibility a serious issue, but oversized enough to make decision making a nightmare. The word 'initiative' is the most abused in Riot's vocabulary. Responsibility and recognition are not earned by being great at what you do, it's earned by loudly championing -something- whether it comes to fruition or not. Lots of politics, bureaucracy, and red tape. Important teams were having their bandwidth squandered by the aforementioned initiative owners all insisting their cause is worth working on. Lots of playing it safe content-wise. Unique ideas get pressed into molds so they can instead be grouped and bundled up according to the (coincidentally subjective) interpretation of 'data'. This is further complicated by Riot being a global company, making it very difficult to take risks. This one's personal, but unlimited PTO actually made it feel pretty bad taking time off. You don't accumulate it, so there's no real feeling of spending it and taking a break that you've verifiably earned. This made maintaining a healthy work-life balance a challenge for me. Because leadership and management responsibilities are essentially given out to whomever asks for them the loudest, career guidance was a problem. Getting any straight answers about how to progress and level up was remarkably difficult when I was actually stuck. Hilariously masturbatory company-or-team-wide e-mails and speeches about humility. Low investment in long-term growth or product health from an engineering/tools perspective (This probably isn't news). It seems that there's always some shiny new feature or initiative being chased instead. The desire to amass the industry's best talent and the apparent aversion to telling awesome people that they're being awesome is not a good mix. Creating awesome stuff on teams packed with talented people and then getting no recognition for it even at a team level became incredibly draining for me. All in all, it was an incredibly stressful place to work.