I love that I can get an unlimited amount free books that have to be returned. That way they don't end up cluttering my shelves for years. Plus, the library provides a huge selection of material to challenge my children's reading levels while still keeping their interest. Mostly, though, I like the free part.
I hate that I can get dozens of free books in one trip that have to be returned. More often than not I miss out on the free part and pay a late fee and/or lost book fee at almost every visit to the library. I didn't make it there to return our books on time today, so tonight I sat down to renew everything online before the library closes and the fines begin. I was horrified to see that we have 25 items out, and as I scrolled through the list of checked-out books I was more horrified to realize I've never seen most of these books, even though they are supposedly in my house. I recognized four titles that I've read many times in the past 21 days because they were the lucky few that turned out to be my kids' favorites. Those select four are in the basket waiting to be returned because I make sure they are put away each night. Additionally--of course--two of the items didn't renew, so now I'll have that familiar fine waiting to greet me next time I go back to check out more books I can't keep track of.