We've also used Netflixs for a while and love it. I've watched more movies since we joined than I have in all the previous years. I love the fact that I can watch at my liesure and do not have to worry about due dates. If I keep a DVD for 3 weeks, so be it.
We've had a couple of problems along the way -- nothing major. Occassionally, their shipping gets a snag in it and it takes longer for them to log in/sent out new DVD's. Only once did we receive a DVD which had a problem -- it was still watchable, we just missed a part of it. Their offered to send a new copy when the problem was reported.
I can't imagine ever going back to a video store for rentals.