I only rent one movie a time and a few times they were a little slow, but 80% of the time that's the post office.
I have never had a serious issue with them. A few discs messed up mid movie but most were fixed by cleaning them.
I spend $9 a month and get 4 movies, that's $2 a week when it would be $5 to rent a movie in a store. It's a great service and they don't screw with you like Blockbuster does with changing your plans every month.
And the only time they changed their polices is when they added free movies (postive of cost) and they lowers all the plans by a $1 or 10%.