The book I'm writing has footnotes.
The reason I'm using them is because I've found that it's the best way to convey certain bits of information, whereas if I did it in text it might come across as info dumps. There is another reason, too. The footnotes are a mixture of fact and fiction, and contributes a sense of reality to many of the metaphysical concepts in the books, helping (I feel) to ground it.
How do you feel, as readers, about the combination of the two. I'd be curious to know. It won't stop me using them, though :)