It depends what you're measuring.

Don't get me wrong, my experiments with true-vibe-coding (i.e. don't even look at the code) are as yours, that the result is somewhat mediocre*.

For some cases, and I try to push beyond the limits of what LLMs can do in order to find those limits, they suck. I'd describe the output as like that of an overenthusiastic junior who reinvents the wheel badly rather than using standard approaches even when told to.

For other cases, I know that mediocre code is actually good enough: well before LLMs happened, I've seen mediocre code that still resulted in the app itself being given meaningful public accolades.

* Though, as per previous comment of mine, I can't help notice that the mediocrity is doing more and more of my previous career: https://news.ycombinator.com/item?id=46989102