Works consistently well for a whole pile of client websites hosted on a shared (reseller) account. I've had many issues with similar plugins so was happy to find something that wouldn't simply "hang up" when server response was not snappy enough.
Minor suggestion - It'd be great if I could choose to back-up the entire wp-content folder as a single .zip file (would make it a lot quicker to restore broken sites).
Note - I do have issues with the download buttons in the Dashboard (files are present in AWS) not working consistently. Not sure if this is due to my own configuration (I don't keep local copies of the back-ups, just S3) or a bug in the plugin. Not too worried since I can still go into my AWS console to grab those files.