Well, it was fun while it lasted. The Turtle was introduced in this episode in a great way, as it turned out that Cisco had been hunting him all along, but Barry and the audience weren't let in on the secret. He makes sense as a villain for this show, because he's the opposite of Barry - slowing things down rather than speeding up. He was portrayed pretty well, and there was a sense of menace to him, and probably some potential to become a recurring cult villain. And then Harry Wells appeared to kill him, and drained his power. Is one appearance all we're going to get of Cisco's white whale, or could there be scope for him to come back again in the future? It seems unlikely right now, but hopefully it is the latter.