Net Library

I was excited to try out NetLibrary - but wasn't as impressed with the outcome. Unfortunately, Netlibrary wasn't very user-friendly. I didn't find as many results with the search box - but ended up skimming though the subjects to find results. I was hoping to find some new titles (I'm working on reading Newbery winning titles), but I only found older titles. I did put about 10 titles into my favorite file - including the Anne of Green Gables series and The Hero and the Crown, etc.
So, from what I understand - you can check out a title and then download it to your Mp3 player - but then it expires after a certain time? How does the downloaded book stop working? I'll be curious to see how that all works out.