The immediate benefit is the ability to access IPv6-only services on the Internet. However, there are very few of those so unless you know of any specific ones you need, you probably don't have to bother.
There is also the benefit of being able to directly access any machine on your internal network without having to bother with mapping ports on internal machines to other ports on your router.
There are also benefits such as more efficient routing for example, and much simplified network management on your internal networks. That is, once you get all the initial setup done.