Upgrading over the Internet is an option, and that option is already there if you want it. I chose to download an ISO image because I was installing it to a PC that didn’t have anything on it, but the ISO has an upgrade option if you boot off it.

I wouldn’t expect too many problems, at least not related to upgrading over the Internet. That’s pretty much a solved problem at this point. There are several ways to check each file’s integrity before starting, and if any given file doesn’t pass the test due to corruption or tampering, the setup can simply re-download it. And if one or more of the files just won’t come down, the setup can abort the upgrade before any damage is done.