Pros
Most Rioters are passionate about the work they do, the people they work with, and the success of their teams. If you're a heads-down worker, if you love the work you do, if you want to work with highly-skilled peers, and if you don't mind lots of politics (especially of the "there's no politics here!" variety), this may be the place for you.
Cons
Riot's alleged "feedback culture" is hit-or-miss. If the sort of feedback Riot claims to value were seen consistently throughout the organization - without regard to sex, gender, age, political bent, team, physical location, nationality, or any of a number of other factors - it could be a powerful tool. Sadly, it isn't. Some parts of the organization are great, but others have more politics and manipulation than nearly all of the other big players in the gaming industry. There are entire teams at Riot wherein providing direct feedback to peers or leadership is a surefire way to get flagged as a troublemaker or worse. Woe to the Rioter who moves from a team with a good feedback culture to one with a toxic feedback culture; they won't be around for long.