Garmin connect is actually a pretty great dive log, I participated in the Dive app beta, was never quite sure what extra functionality it had. Maybe Garmin intends on entering the pure dive computer market? Or they're in the process of buying a dive computer company?
The one thing this makes me think of is, how confident are you that you will only dive Garmin computers for the rest of your life? If you are confident of that, then I can see using the Garmin tool for your dive log.
If you are not, then maybe you should consider using a tool that will load from Garmin, but will also load from other brands, so that some day down the road when you change brands, you will be able to keep using your same dive log application, and have all the dives from your new computer and your old computer all in one place?
Like Subsurface...
Subsurface | An open source divelog
Free, open source software. Runs on Windows, Mac, Linux, and has mobile apps for Android and iOS.
Free cloud storage, as well, with automatic syncing between all your different devices.
Loads directly from the vast majority of dive computers. I normally download my dives into my phone, from my Shearwater, via Bluetooth, while I'm still on the boat or at the dive site. It auto syncs to the cloud. When I get home and open Subsurface on my laptop, all my dives are already there. I prefer typing on my laptop, so that is when I enter my notes about the dives (though I *could* do it on my phone or tablet, if I wanted to).
I have one dive log (in Subsurface) that has all my dives, downloaded from about 7 different computers, from at least 4 different brands (Oceanic, Shearwater, Hollis, and Seabear).
It would bug the crap out of me if all my Oceanic dives were in one software log, all my Shearwater dives were in a different software log, etc.. Migrating the data from one tool to another is USUALLY possible, but not always. And when it can be migrated, it's still usually a pain in the butt.
With Subsurface, I have numerous dives where I dived a Shearwater and a Seabear on the same dive. I downloaded from both and Subsurface automatically merged the dives in my log, based on date/time, so I have only 1 dive showing in my log, but I can view the data from either computer that I had on that dive, to compare them.