According to Blizzard, “The Legion beta test includes the new Demon Hunter class, the starting experience for the Broken Isles, the new level-up and max-level zones, the new Artifact system, and much more. Beta testers will be able to create characters using level 100 templates, so they’ll be primed and ready to explore the newest content.”
Blizzard also notes that there will not be any NDA placed on the beta, meaning that you’re more than welcome to share what you’ve discovered with your friends. Alternatively it also means that you can look forward to more videos posted on YouTube describing the beta experience. This isn’t an open beta so if you did not receive an email letting you know that you have been chosen, then we guess that’s just too bad.
In the meantime World of Warcraft: Legion is expected to be released by the 30th of August, 2016, meaning that we still have several months of beta testing ahead of its release which will hopefully ensure a smooth and relatively bug-free launch.