I've used Google Photos as an automatic photo backup since 2011. I didn't start using the iCloud/Apple Photos combo until late in 2015. I spent downtime during the past few days making sure copies of everything pre-2015 was moved over to Apple Photos because I'm think about taking all my pics and videos out of Google. Why? Because I am becoming convinced that Apple is more concerned about my privacy than Google is. Exhibit A. I'm also tired of giving Google ten dollars a month for storage.
Why haven't I moved everything to Apple Photos before now? At first I was taken back by the fact that keeping everything in Apple Photos means you can't delete pics off your devices and just store them in the cloud. You can in Google Photos. Google Photos also automatically does a bunch of cool stuff with your photos. Without damaging the originals, they will string together a loop of several similar pictures; they'll create videos of related pics set to music or maybe apply special lighting to a picture they think is a particularly good one. I've enjoyed this over the years, but more and more I hear perspectives like the one linked above. It makes sense, and is a little unnerving.
Unfortunately, there is no way to move things directly from one cloud service to another. In the Google Drive sync preferences on my MacBook, I selected the folders I wanted to download, waited on the download to finish, and then import them to Apple Photos. I had about 30gb worth of room on my MacBook so I selected only a few months to downloaded at a time, and then after importing them to Apple Photos, I removed them from my MacBook and grabbed a few more months from Google Drive. I added over 15,000 pics to Apple Photos (bringing the total over 20,000) and several hundred videos. 24 hours later, a couple thousand of them are still uploading to iCloud. What's left must be videos because the last thousand is taking forever. Granted, I'm working with horribly slow internet.
Though not fast, the process was pretty simple. My only lingering concern is that some really important picture didn't get downloaded. I've deleted Google Photos from my mobile devices so I'll no longer be uploading photos there, but I don't think I'll be deleting my stuff from Google Photos for a while — not until I'm absolutely sure every thing has made its way over. I really don't like the prospect of losing any part of the first few years of my kiddos' lives.
I'm looking forward to the improved file compression promised in iOS 11, but for the time being I still have enough room on all my devices. It's nice to know that basically every digital picture I've taken in my life is on all of my devices and in the native Apple Photos app. For the first time the data isn't scattered across two platforms.
One thing I'm still not clear on, however. Apple lets you save space by keeping "optimized" versions of your pics on your devices, while the originals live in iCloud. But what happens when I share a pic or video from one of my mobile devices? Am I sharing the optimized version or the full sized version?