I have had various Garmin GPS units over the years and currently have the RV 760LMT.
I like to keep my units up to date so I have updated both the device firmware and maps many times. Touch wood but I have never had a problem. The map updates are not fast, they take several hours but they have always worked for me. I always do the updates at home before I leave on a trip. I wouldn't want to try and update them using campground WiFi for example, I think that would be asking for trouble.
Garmin have had several approaches to software updates over the years, their current utility is called Garmin Express and it takes care of everything. It recognizes the device I connect, checks for updates and then installs them.
I am sure there are other Garmin users who have had problems, but that is my experience.