Connotation: The connotation is almost always positive or neutral. It's seen as a compliment to the person you are conceding to and reflects well on your own character.
Formality: As a Chengyu, it's inherently somewhat formal. However, it is commonly used in everyday conversations among educated speakers, often in a lighthearted or self-deprecating way.
In Competition: After a game of chess, a sports match, or a debate, it's the perfect phrase for a good sport to use.
Admiring a Skill: You can use it when you are genuinely impressed by someone's talent in cooking, painting, programming, or public speaking. It's a powerful form of praise.
Humorous Self-Deprecation: It's often used among friends to joke about one's own shortcomings. For example, if your friend solves a complex problem effortlessly, you might say it with a laugh to praise them.