With the API, you can basically customize the session ranging from providing batshit bananas replies (by setting high temperature) or almost deterministic replies (by setting low temperature) with personality controlled by the system prompt, so you can make it "friendlier", "less formal" or anything else.
It is still as slow via the API as via ChatGPT though, which kind of sucks when you're using it for longer passages. I do wish it was just about 100% faster.