Only interested in non fiction and last I looked the catalouge was less than 2000 titles.
But works really well, easy to use, easy to reserve etc.
By the way Google is your friend to use them on the Kindle.
In case you did not know, Auckland Libraries also subscribe to Freegal music service which lets you download three tracks (in the case of Auckland Library) per week for free. You keep them forever (they never expire) and the licence entitles you to burn them to CD. Mine go straight into my iTunes library on download. Not everything is available, but still a massive selection and all of Sony's catalouge.