Honestly, it's been fantastic!
It's such a blessing to not have to wonder about sun exposure. The app looks good from a design perspective and has great info, but maybe feels just a little rough around the edges. I'm using an iPhone 14 and the edges of some of the screens seem to be misaligned. I'm sure with a few more iterations you'll get there. Biggest gripe would be that the widget is currently useless. It's just a clock, but there are a ton of in-app dashboards that I would like to see displayed on my home screen.
Feature wise, I would like to see a lot more notification options. Biggest missing one is a notification for adequate Vitamin D exposure. I'm often trying to balance skin aging with vitamin D production, so a notification on when I hit that balance would be awesome. Just like the reaching max exposure notification, that works really well.
Notifications around when the sun exits or enters UV 1 - 2 would be helpful as well, essentially notifying you when sunlight is in a healthy range. Honestly a whole suite of customizable notifications would be great. For example I love that you have the sun forecasts that show you at what time to wear a cap, sunglasses, and sunscreen. So perhaps a notification on when you should put each of those on and take them off would be great. Essnetially the goal here would be to help nudge positive sun habits in your users. Of course, control of these notifications would be key as each user has different preferences on what they consider a disruptive level of notifications.
Anyways, you can count me as a happy user. I'll be posting about your product on social media soon.