Pros
People: I'm surrounded by incredibly talented, intelligent people who constantly challenge me to improve. I've learned more at Riot than I ever thought possible, and I see no sign of that stopping. Everyone is incredibly enthusiastic about League of Legends, and that genuine passion is infectious. Culture: Almost everything about Riot I'd describe as "high energy," dialed up to eleven. The culture is hugely focused on self-improvement and iteration. "Challenge convention" is a common phrase. Riot underlines how incredibly important understanding the player's perspective is, so we're always playing the game and trying to think globally. Open communication and seeking alignment is encouraged. Perks: So many perks... There is endless free food. Catered lunches happen frequently, and there's always leftover sandwiches, pizzas, greek food, etc. IT is always stocked with candy. The beverage machine is only 25 cents a drink. There are show-and-tells and other company meetings with free beer multiple times per month. There's birthday cake for everyone at the end of every month. To offset the incredible availability of free calories, there are dozens of sports and exercise groups that meet up after work... fencing, kickboxing, soccer, dodge-ball, boot-camp, you name it. The gym near the office is also subsidized to $25 a month (Though we'll be moving offices in the next year or so). There's a yearly company trip, all expenses paid, that generally also allows significant others along. Oh, also, you have "discretionary" time off, so as long as you don't go crazy, your vacation days are up to you. Baller. Work-life balance: Honestly, pretty good. I know many people who work late or sometimes come in on the weekends, but it's by no means expected or required. I leave around 7 PM every day and try to never come in on the weekends. That said, to learn and grow at the rate the company expects, I do sometimes feel that I need to use my free time to study and learn new techniques. Outlook: Every year the company is topping itself... the quality of talent coming in is staggering. The game is continuing to grow in popularity, with the eSports scene going from low-production-value streams with a few thousand viewers to record-shattering productions at the Staples Center in the space of two years. When we go on a yearly company trip, it's Las Vegas one year, Dominican Republic the next. I'm going to try to hold on as long as I can. TL;DR - The only constant at Riot is change. It's continually evolving and, so far, usually in the right direction.
Cons
Compensation/ Promotions - While my experience has been mostly positive, I know some who have had negative experiences. I'm a fairly young developer - I got into the company early, and was able to grow and get a few promotions along the way. I still have some opportunities ahead of me if I work hard, and overall I feel well-served. That said, I also have some more senior friends who feel the opportunities are lacking. I know some who took demotions or paycuts when they joined Riot. I know some who are still in that position after being at the company for years, or who feel they don't see eye-to-eye with their managers on what their compensation should be. Some departments have a reputation of having more stingy managers than others. On top of that, there is no bonus structure similar to many other game companies. Your mileage may vary. Development Uncertainty - Everything is in a constant state of change at Riot, which means that teams form and are dissolved constantly. Resources are shuffled around, and sometimes that awesome tool that was going to take a year to make gets cancelled six months in. Sometimes a team changes the game code and then dissolves when you need to ask them how it works. (To be fair on this last point: it is very much known as an issue by management and the engineering discipline is working hard to improve code ownership) In summary, while constantly changing allows us to be really agile, there's definitely some pain associated with constantly re-calibrating.