IANAL, but here's my takeaways from reading the complaint:
* There is heavy emphasis on the "Founding Agreement" as the underlying contract. (This appears to be Exhibit 2, which is an email to which Musk replied "Agree on all"). Since I'm not a lawyer, I'm ignorant on the interpretation of a lot of contract law, and there may be finer points in case history that I'm missing, but... where's the consideration? The "Founding Agreement" in general reads to me not as contract but preliminary discussions before the actual contract is signed.
* The actual certificate of incorporation seems more relevant. Also, it's a Delaware corporation, which makes me wonder if Delaware wouldn't be a more appropriate jurisdiction for the dispute than California. Granted, I know Musk now hates Delaware because it's ruled against him, but that's not a reason you get to file suit in the wrong venue!
* I noticed that Musk's citation of the certificate of incorporation has an ellipsis on one of the articles in contention. The elided text is "In furtherance of its purposes, the corporation shall engage in any lawful act of activity for which nonprofit corporations may be organized under the General Corporation Law of Delaware." ... Again, I don't know enough to know the full ramifications of this statement in jurisprudence, but... that seems like a mighty big elastic clause that kind of defeats his case.
* Musk admits to having continued to contribute to OpenAI after he expressed displeasure at some of its activities (paragraph 68). That substantially weakens his case on damages.
* Much hay made of GPT being AGI and AGI being excluded from licenses. No citation of the license in question seems weak. Also, he pleads 'However, OpenAI’s Board “determines when we’ve attained AGI.”'
* Paragraph 98 asserts that OpenAI fired Altman in part due to its breakthrough in realizing AGI. But the conclusion I've seen is that Altman was fired for basically lying to the board.
* Paragraph 105: However, the OpenAI, Inc. Board has never had a fiduciary duty to investors. ... interesting theory, I'm not sure it's true. (Can some lawyers chime in here?)
* There are essentially two underlying causes of action. The first (comprising the first two causes) is that the Founding Agreement is a binding contract between Altman and Musk that OpenAI breached. I'm skeptical that the Founding Agreement actually constitutes a contract, much less one that OpenAI is a party to. The second (comprising the last three causes) is that, as a donor, Musk is entitled to see that his money is used only in certain ways by OpenAI, and OpenAI failed to use that money appropriately. There's no pleading that I can see that Musk specifically attached any strings to his donations, which makes this claim weak, especially given the promissory estoppel implied by paragraph 68.
* The prayers for relief include judicial determination that OpenAI attained AGI. Not sure that is something the court can do, especially given the causes of action presented.
Overall, I don't think this case is all that strong.