GPT-J feels much worse than GPT Davinci on the lack of instruct capability. My understanding is that it was not trained on instruction-completion data as much. It's great for text classification, summarization, and other tasks.

However, I also feel like it hallucinates/gives wrong outputs more. TBH i love what Eleuther is doing and GPT-J has its merits, but it feels not ready for primetime. I'd think of it as most similar to GPT Curie.