This was a huge upgrade from my Garmin 530. I think the UI is the best out there, especially for Strava live segments. No bugs or issues yet, very simple to get going. Get about 13 hours of battery life.
I've been using a 5 year old Wahoo Bolt up until I got the Karoo. It is more simple to use and does SO much more without needing a complicated manual to figure it out. I'm enjoying it a lot. I do wish that it had a mounting system that was more compatible with all the mounting systems I currently have.