Learn something u can not get in even top university labs, and the programming skills from top programmers. They will offer u a mentor and u can make a study of the code they provide you with.
Cons
Long working hours, tedious and boring, talking not permitted.
Good research culture;
Flexible work environmnet in most of cases;
Smart people, from who you can learn a lot on how to do research;
Somehow a good place to do research for a PHD, especially in China, Beijing.
Cons
Bureaucratic;
NO long term career for master degree, and for RSDE;
In a research lab, they need people to take the engineering work, but they don't rewrard people who take engineering work farily. So either you should insist on research work only, or you should consider move on after a few years.