I think people's opinion of him will improve as time passes. Joust is a very strong mechanic. I thought he was garbage until I noticed he had a power icon. That could make him pretty scary late game.
That being said, it doesn't really feel like Gregor. We're talking about the poster boy of the deadly keyword here. AFAIK This is the only Gregor Clegane card out of 6(?) without the word kill or killed somewhere in the ability text.

You know if this was the first version spoiled of some great Bara character, you would be the one posting 'nonsence'. 