I found it useful for learning to write prose. There's nothing quite like instantaneous feedback when learning. The downside was that I hit the limit of the LLM's capabilities really quickly. They're just not that good at writing prose (overly flowery and often nonsensical).

LLMs were great for getting started though. If you've never tried writing before, then learning a few patterns goes a long way. ("He verbed, verbing a noun.")