I've been saying it all along to my peers, yes indeed he did have a very nice XMas game, his main problem this year so far though has been consistency.
Him and Harden are still learning how to coexist and already as you said the month of December was much better than November. I also thought they were misusing him earlier in the season, they had him spotting up out on the perimeter while Harden basically ran the point which to me never made any sense since he's a poor jump shooter. They seem to have totally forgot that his strength is his penetration, but lately especially since McHale came back they've gone back to that, and more noticeably they've sped up the tempo and now are pushing the ball rather than walking it as they did in November.
Once he gets a reliable jump shot he should be a pretty good player assuming his all around game will also improve, he'll never be a top tier point guard but he can be a solid top 10, 15.