I have the opposite experience. I have used single HTML page LLM generated slides for demos/presentations, but they were designed in a manner to tell a story in an easy to understand way with animations and aesthetically pleasing manner. So far I have only gotten positive feedback because for most people it was easy to follow the story I wanted to tell and be engaged rather than staring at a power-point slides.

I guess it heavily depends on how much effort and refinement you put into when creating it regardless if you use an LLM or not. I always ask my self would I fall asleep if someone else presented these slides to me, and if the answer is yes, then I keep on refining it till it meets my standard