It’s great at doing stuff that is routine, well-understood, done and documented and discussed many times before. “Boilerplate”. But also summarization, brainstorming, assisting a human unfamiliar with the body of knowledge.

It is bad at doing novel things or subtlety. For example when I ask for help with Postgres queries, LLMs frequently give me made-up syntax or combine features from several different databases like Oracle, MS-SQL, Postgres into a single answer.