In TV series, we can't directly judge whether he is a "good guy" or a "bad guy" because it involves many complicated factors, such as personal behavior, motivation, moral concepts and so on. However, we can see that as a detective, he works very hard in investigating cases and sometimes takes some unexpected methods to solve problems.
Generally speaking, He Downey is a relatively complicated character, which cannot be simply described as "good guy" or "bad guy".