AI is not infallible. Whether it's the free or paid version. The output can vary greatly depending on the subject matter. Whether that's writing on a certain topic, doing research for a specific project, or asking it to do the heavy lifting on research data. You have be knowledgeable enough to spot bad output. I've had to correct AI output on building code-related issues. When I ask it to compare hi-fi component specs and performance in side-by-side comparisons, it will give me incorrect or outdated spec information that I have to spot. Does AI have useful applications? Yes, but if you're only using it for basic Q&A, or as a beefed-up search engine, then it will "feel" limited in its application.
The trouble with using AI for basic queries is that it defaults to scraping relevant data it thinks you are requesting. The last thing I would use AI for is health-related questions. Because, as others have mentioned, it doesn't know your specific health history, lifestyle, etc., that your regular PCP would know. AI also hallucinates a lot.
Another thing I've experienced teaching grad courses is that students relying on AI output as 100% correct will not double-check output validity. In this respect, AI use can encourage intellectual laziness on the part of the user if they don't have enough experience knowing how to research for relevant information that isn't easily available. Especially behind pay-walled technical / academic sites.

