I agree, it's similar to Joda for Java. Sure, Joda does some things that exist in the standard library, but you can be sure that by using Joda that you're getting it right in all kinds of twisted scenarios you never considered.
It's pretty straight forward to migrate from Joda to Java 8's builtin classes though. Just remove the dependency on Joda Time and let the compiler tell you which files to fix.
This blog post lists which Java 8 classes replace their Joda Time counterparts: