The two most obvious are:

* Disconnection from human beings, and in particular, human emotion.

* Hallucinations.

The first is very true, but I feel it is different from the phenomenon in humans. Even the most disturbed human being still has most of the basic human functions such as a body, a formative childhood and social interactions of a nature that an LLM will never have had.

I do not see LLM hallucinations in the same light. If there is one thing LLMs don't have, that is real creativity. They work on stochastics, and the blending of pre-existing material. Human hallucinations are often creative, and there is an overlap with artistic creativity which has been frequently commented on. LLMs as such does not seem to have a fully formed worldview as even a delusional human would do, and I haven't seen evidence of, say, paranoia in an LLM.

Anyway, I could have probably said that more briefly. There are many other angles of course.