Pros
Riot is a company made up of gamers, and for that reason the culture in the office is centered around gaming. This gives the office a very relaxed feel, but does create a noisier environment that can make it hard for some to concentrate. With the massive growth Riot has experienced, opportunities to grow and take on new challenges abound. Although the number of these open spaces is rapidly declining as the company begins to match it's growth curve, leadership does a good job of encouraging individuals to step into opportunities and problem spaces in front of them. In adopting the open PTO policy, Riot decided to put the onus of taking vacations on the employees - which can actually make it tougher to take a longer vacation when you don't see a number associated with your 'earned' days off. It does, however, make it very easy to keep illnesses at home and prevent wide-spread sickness.
Cons
Riot is extremely young. This can be beneficial when considering how easy it is to get along with like-minded individuals, especially in a gaming culture, but can very much be a hindrance when looking for support or experienced mentors. Although the company is headed in the right direction by bringing more experience on board, there is still a ton of room to group. Additionally, the lack of workforce veterans has caused issues with inexperienced management not properly setting expectations, resulting in decreased performance and, at worst, attrition. The last issue is work/life balance. Although the company has established an open PTO policy, frequently many Rioters will spend most of their waking time at work. This creates a sense of missing out for those unable to spend as may hours in the office, and is ultimately unhealthy. Lastly, the culture around being gamers and curious problem solvers is a huge boon to the company, but the other side of the office culture can quite the opposite. The idea of a bro culture is slowly establishing itself in Riot and has the unfortunate side effect of alienating stellar individuals.