I'm not using a G1, though I strongly considered it. Instead opted for an MK2s. At the time there was a rebate on the MK2s. Between that and a discount I was able to get, the cost was pretty close to the G1 Solar.
The thread here has a pretty good discussion of it. Later pages have reports of some who have used it and recommendations.
New Garmin Dive Computer: Descent G1
If it's anything at all like my MK2s, I wouldn't hesitate to use it. Main difference would be the screen. If the monochrome screen is fine for you, then I think you'll like it. My MK2s is a backup to my Perdix AI, and apart from the AI capability, there really aren't any capability gaps between the Garmin and the Shearwater. The two track real well together, which makes sense as they use the same deco algorithm with same presets or custom GFs. The only functional difference I noticed is that the Garmin seems a lot more sensitive to depth changes than the Perdix. When comparing the profiles in Subsurface, the Garmin profile has ascent warning
, but the Shearwater profile does not. Not a big deal, and when it vibrates, I know to just slow down a bit.
Edit to add:
A couple other thoughts. When you first get the G1, go through all of the activities. You can make things a lot easier if you keep the activities that you use infrequently off of the main activity loop. You'll still be able to use them, but they'll be further down in the list. If the G1 is anything like my MK2s, you should also be able to customize the dive screens, and there are several options you can pick from.
The Garmin DCs don't allow direct wireless downloading to Subsurface, but it's really not a big deal. They download to Garmin Dive and Garmin Connect without any interaction from the wearer. And from there, can be easily exported to Subsurface, or other log software presumably.