I've found that to be accurate when asking it questions that require ~PhD level knowledge to answer. e.g. Gemini and ChatGPT both seem to be capable of answering questions I have as I work through a set of notes on algebraic geometry.

Its performance on riddles has always seemed mostly irrelevant to me. Want to know if models can program? Ask them to program, and give them access to a compiler (they can now).

Want to know if it can do PhD level questions? Ask it questions a PhD (or at least grad student) would ask it.

They also reflect the tone and knowledge of the user and question. Ask it about your cat's astrological sign and you get emojis and short sentences in list form. Ask it why large atoms are unstable and you get paragraphs with larger vocabulary. Use jargon and it becomes more of an expert. etc.