Positive traits: High level of patience, good leadership skills, ability to make good judgments, high level of meekness/humility
Negative traits: Can be too passive or lenient, tendency to make judgments too quickly, lack of imagination, opposed to change
Notes: One of Lestrade’s best qualities is that although he is a good leader, he is also willing to step back and let others take charge if it is for the benefit of others, such as when he lets Sherlock Holmes solve cases for him. Instead of being offended or jealous of Sherlock’s rude comments and superior intellectual prowess, he has enough humility to let Sherlock take over because he knows that this will be in everyone’s best interests. This is evidence of his selflessness. He also has a large amount of patience to be able to deal with Sherlock’s behavior and attitude, as well as other problems that may arise out of being the boss of a large number of people.
Part of being a leader, of course, is making difficult decisions, which Lestrade has his fair share of. He is a good judge of character, and he seems to trust his instincts: he puts faith in Sherlock when no one else did and believed that he is “a great man”, despite overwhelming evidence to the contrary; however, it seems that he can also sometimes be too confident in his decisions or make judgments too quickly when under pressure, particularly from other people with oppositional positions (such as making the decision to arrest Sherlock on suspicion of kidnapping because of Donovan and Anderson). Lestrade can sometimes be too generous, giving Sherlock more leeway than he knows he should, and it is easy for some people to take advantage of this nature (such as his wife cheating on him).
As for lack of imagination, I am taking Sherlock’s word for this. In the original canon, Sherlock describe Lestrade as being an all around good detective except for one thing: he lacks imagination.