The major reason I prefer fbDownloader over this app is because PhotoGrabber is rather restrictive when it comes to you specifying what you want to download. For example, it's either download "all the albums" or nothing. In fbDownloader, you could choose which albums you wanted. Here, you get the whole lot.
But the biggest plus for PhotoGrabber is that you can pull in all the comments and tags. If you choose this option, then PhotoGrabber generates an HTML page so you can view this information alongside the photos. This in theory means that you could back these pages up to your own personal domain as another online backup.
PhotoGrabber is under active development. If you make backing up something of a religion, then PhotoGrabber is a tool you should use on a continual basis, as well as keeping an eye on the project page over on Google Code.
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