It is true. Elm has taken some syntax away and native packages, and made the language better by being simpler and error free (I have never had a runtime error).
Upgrades since 0.17 have been pretty easy too - there is automated tooling that does the heavy lifting.
Migration ease really depends on your use case. I am currently doing the upgrade on a production application, and some changes (dates, navigation/fullscreen) have been a pain.
The more automatic stuff that can be caught by the compiler is usually a breeze, though.
Upgrades since 0.17 have been pretty easy too - there is automated tooling that does the heavy lifting.