Here are my thoughts, let me know what you think of them or what you would change.
Has an ancient samurai look to him. Kinda looks like Noisy Boy from Real Steel but a little more different.
Like the IDW comics he was once a Decepticon, but turned his back on them to regain his honor.
Perhaps he doesn't say a whole lot. But when he does it is right to the point and meaningful to the task at hand.
I could see him as this bug eyed brainy science nut, like Perceptor, but maybe with a little bit of an edge to him.
He also could make weapons for his team mates like Q. did in DOTM, only they work just a little more efficiently.
I'm sure he'll be this gruff old bot who still knows how to kick Con tailpipe. He's a little like Ironhide, but a little more crankier.
As for his look I think it is the bearded looking Bot we saw the face of on that pole. Would make sense I think.