I am trying to use it now, but it is confusing me.
First of all, let's talk about app naming. When I access photos.google.com, the app (in "App Downloads") is named "Desktop Uploader". But when you download it, the name appearing on your Mac is in fact "Google Photos Backup". Got it. But here's the big problem...
When I launch Google Photos Backup on my iMac, it shows me a dialog that says:
Choose backup sources
- Cameras & Storage Cards
- iPhoto Library
- Desktop
- Pictures
And at the bottom I have "High quality" chosen, of course, so as to get the free unlimited storage plan. (And no, that doesn't bother me because the best camera I have is a Lumix GX-7 which is 16MP, so my photos will NOT be down-scaled, and my 1080p videos, will not be altered either.)
But I haven't clicked the "Start Backup" button on that dialog yet. I upgraded (downgraded??) to Photos (from iPhoto) a couple weeks ago. All my new photos since then are now stored in /pictures/Photos Library, not in the old /pictures/iPhoto Library. I know this to be true because if I launch iPhoto, I don't see any new photos that appear in the Photos app — only my photos prior to using the Photos app.
Hence, all my photos are actually in "Photos Library". But the Google Photos Backup app foolishly asks to import ONLY from "iPhoto Library." True, it also has a checkbox for "Pictures", which I assume means /pictures. But if I choose only that, how do I know the Google Photos Backup app will pull photos from "Photos Library"?
It's all very confusing to me, so I quit the "Google Photos Backup" app and am now searching the web for experiences of others so I know what to do. That's how I found this thread, in fact.
It's shocking that I cannot find any Mac users talking about this. This was the only thread I could find today on-topic.
ADDENDUM:
One other related point. I uploaded all my photos and videos on my iPad using the mobile iOS app. Photos are great — no problem. But when I create a Shared Link for my 1080p videos (which look perfect in 1080p within the Google Photos app, by the way), the video opens in Mobile Safari and displays as what appears to be 480p and highly compressed. Quite frankly, the shared videos displayed on my iPad, look horrible, awful, heinous, and unthinkably bad. But when I try the same shared link on my iMac and load it in Safari, I see the video appear in 720 by default, and there is the familiar YouTube-style cog in the bottom left that I lets me switch to 1080p. But that cog does not exist when viewing your shared video links in Mobile Safari! So you have to be satisfied with highly-compressed 480p on your retina mobile devices! Unthinkable!