The criticism of cliff's notes is generally that it's a superficial glance. It can't go deeper, it's basically a summary.
The LLM is not that. It can zoom in and out of a topic.
I think it's a poor criticism.
I don't think it's a silver bullet for learning, but it's a unified, consistent interface across topics and courses.
Sure, but only as long as you're not terribly concerned with the result being accurate, like that old reconstruction of Obama's face from a pixelated version [1] but this time about a topic for which one is, by definition, not capable of identifying whether the answer is correct.
[1] https://www.theverge.com/21298762/face-depixelizer-ai-machin...
It's unlikely to make up the same bullshit twice.
Usually exploring a topic in depth finds these issues pretty quickly.
If LLM's got better at just responding with: "I don't know", I'd have less of an issue.
Some topics you learn to beware and double check. Or ask it to cite sources. (For me, that's car repair. It's wrong a lot.)
I wish it had some kind of confidence level assessment or ability to realize it doesn't know, and I think it eventually will have that. Most humans I know are also very bad at that.