I have used it, several times - I will admit to being a Midjourney customer.
The thing is, what it generates isn't really usable for client work - you can't just plug in a prompt, and get a logo out. If you spend maybe an hour refining your prompt and doing 100+ renders, maybe you might get *something*. But it'll never replace the artists who can take a prompt from you and *create* something to order, not without many, many more hours.
What it does do, quite well, is allow for ideation - taking a concept and giving you something you never expected from it. Interestingly I don't think that's something a human can *necessarily* do well. Sometimes you need an external influence to generate new connections and as a vehicle for discovery by taking things I've never seen and showing them to me in new ways, that *can* be interesting.
As for it being ethical, that's a very, very different question, and a difficult one. It is of course a model trained on a volume of existing work, and doubtless at least some of it was not licensed/paid for/approved by the artist. Scraped from the web. Their core source material was produced with dubious ethics. My own stance is conflicted; I like the idea of the ideation I get out of it, but I'd also like the artists to be compensated. But I'm not using it in lieu of actual artists, I'm using it for ideation, idea generation, which where relevant I'll take to a real artist to make a final design out of. But even this eats at the concept artist tier, and will continue to eat away at the bottom-most tier of the market - the folks who aren't good enough to make it as professional artists, but whom eke out a living doing commisisons. As the technology improves, that segment will likely disappear.