I use Hoopla through the Capital Area District Libraries and I absolutely love it! I agree with the other comments that the service's strengths seem to be nonfiction ebooks, audiobooks, and graphic novels. If you choose to get Hoopla, I would add that providing information to patrons about how the borrowing and lending limits works would be a good idea. As a user it's tempting to just borrow everything you might want to listen to, until you realize that you're taking up a limited number of borrows system-wide to do that. 

Chelsea