my experience is that it's pretty subpar

Are you using code interpreter? It's better.

The mobile app doesn't offer it though, and also has a system prompt that causes some strange behavior - sometimes it will put emojis in the text and then apologize for using emojis.

Care to share a GPT conversation you’ve had? I’m interested in what sorts of prompts lead you to this opinion. My experience is the opposite.

A bit too much of a hassle. But if you're willing to share some of your good experiences, I'm curious