Once I figured out all the authentication stuff it was super easy to use and I managed to back up all my Flickr photos onto my computer before I deleted them all from Flickr :-) Thanks!
4/5 for documentation because the "flickr.auth_token" configuration item was pretty tricky to figure out and the docs weren't much help. Here's some notes from when I did it in May 2012 - your mileage may vary if it is after that date when you read this ;-)
It was a pain to install, and then I struggled with some issues about getting it running. Now that it's going, though, I can delete my iPhoto store and just back up Flickr. I won't lose comments, notes, descriptions, tags, or anything else that I didn't have in iPhoto. What a relief!