For photos, its the best, in my opinion. Has a simple interface, can add tags easily, and organize them too, by tags or folders. You have both views available all the time. I use it for backup too, 'cause I can upload one group of photos (be it a folder or all the ones under a tag) to a SkyDrive folder, and set permissions there for only my family and/or friends to see.
And I love its import photo utility, when I put a memory card, etc. Want to copy all the photos or organize them by groups? You can do it right in the moment they're been imported. Always keep your photos organized and tagged from the beginning. You'll avoid painful search later.
So, if you look for easy and practical personal photo management, it's the best.
NOTE: Not to be confused with Windows Photo Gallery, the one that comes with Windows Vista. That one only have an import all your photos option. And you can only see your photos by tag, but no by folders, that doesn't work for me.
"A complex system that works is invariably found to have evolved from a simple system that worked." -- John Gall, _Systemantics_