Pros
I've been at Riot Games Sydney for less than a year, but I have enjoyed the experience thoroughly. Riot is different from a lot of other workplaces. If you look at the manifesto, that's not there for show, it's something we actually believe in and incorporate into our day to day activity.
When we say we aspire to be the most player focused games company in the world, we mean it. Riot doesn't always get it right, and sometimes they can do some really silly things (hahaha replays/sandbox mode etc. As many Rioters are players themselves, they want these features as much as any other LoL player). But the heart is always in the right place and it shines through when we consider any major decision that will affect the Oceanic Player Base.
We currently have a ~25 person office. Everyone is on pretty good terms with everyone else. I mean, we're all gamers, we all play League (well, almost everyone) and we all share the same mission to deliver player value. We hold internal tournaments, have catered breakfasts twice a week and a catered lunch once a week.
This office is full of very driven people, and it's expected that you are able to manage your own time effectively and deliver results. Nobody's going to tell you what to do, but if you need help, there's always going to be a helping hand. Another plus is that if an opportunity arises that you have the skillset to help out in, you can feel free to put your hand up and do it. Nobody's gonna say no.
This office is very much one about open feedback. If you screw up, you'll know. We're expected to level each other up.
Oh, also, the subsidised vending machines at the office are pretty sweet (no pun intended)
Cons
I wouldn't say there are too many downsides to working here. Sometimes we aim for perfection too much and that can be a blocker to delivering more player value.