Bad Experience for me
I bought the app hoping to make life easier keeping our family iPhoto library the same on 3 computers. There are virtually no instructions, and help takes you to a cryptic web site that starts off talking about “slots”. I was flying blind, and the experience was a miserable failure. I tried to sync a library from one computer to another. The process took 12+ hours over Wifi. When I opened iPhoto on the target computer, the newer photos were not there. I found no information about which version(s) of iPhoto it works with, or whether I need to do something in iPhoto to see the newer photos. I’m on the current version of iPhoto (9.6) and OSX 10.10 on both computers, a Macbook Pro (retina) and a Mac mini.
In the end, to update our photos on third computer I relied on a manual method. I just selected each event in iPhoto on the source computer and selected File>Export to create a folder containing the photos on the target computer. Then I imported the photos into iPhoto. The process for a 1500+ photos in about 6 events took less than an hour.
Bill550 about Sync for iPhoto