Got an opportunity to try out Levels a little while back. The hardware isn't unique to Levels (as they're using FreeStyle Libre CGM sensors), but I appreciated the (re)packaging and onboarding as I wasn't familiar with CGM sensors prior. I was a bit concerned about the application process and if the sensor would be uncomfortable, but it was easy to apply and non-obtrusive. I liked the ability to get rapid feedback and to better understand how my body was impacted by glucose and how exercise also came into play. Levels provide a lot of information and content via their app, which I found to be helpful. They also have an active Facebook community for those who want to interact with others using Levels, which can be quite handy.
On the flipside, the amount of information available felt a bit overwhelming at times. I felt like I needed a tad bit more guidance on what to read and when, and I wish the app could interpret my data and provide more customized recommendations on what I could/should change. Would also note that it's a bit pricey at the moment, but they've acknowledged that before, and I know they're working on that.