While it is a cool reveal, I can't help but be disappointed in the way it was done.
Imagine you are a viewer who isn't familiar with the comics. The reveal would totally fall flat. "He's a green guy named John Jones? Huh? Am I supposed to know who that is? The music and the framing of the scene sure makes it seem like I should. And what kind of alien is named John Jones, anyway?"
That scene was pitched to those of us who know the character and will automatically think it's cool. It should have been aimed more at non-comic reading viewers.
Other than that disappointment (which, admittedly, is rather mild because... well, J'onn J'onnz!), excellent episode.