Vantaggi
A lot of smart people to work with and learn from - experts in machine learning, network technologies, high load server technologies, C++/Python gurus. Interesting projects. Competitive salaries + stock options, good office, medical insurance, free snacks. Company can offer a low-interest loan to valued workers.
Svantaggi
Yandex is big company so you can have absolutely varied experience in different departments. I describe the view from my corner :) Work/life balance strongly leans to work, especially true for team leading positions. A lot of people spend their whole life at job and expect the same from colleagues. New performance review system is based on stack ranking - rank everybody, find several best/worst achievers every 6 months and deal with them accordingly. What if all real worst achievers already left the team? Does not matter - rank everybody, find several scapegoats and give them B/C- rating. Review system is not very transparent, if you get low rating once, you will be under scrutiny afterwards. Products sometimes are rushed to be released before performance review dates, that leads to shamefully raw and buggy releases. Quality of code base and test coverage is strongly varied from team to team. Level of strain is strongly varied in different teams.