This is a solid golf swing. Hunter Mahan has one of the smoothest swings on tour. It is fundamentally sound, and very repetitive. The question for the Americans is whether that swing will keep it's beautiful rhythm under the pressure of the Ryder Cup. The American side certainly hopes so.
I absolutely love his takeaway. The start of his backswing is so smooth. You may have heard of the "one piece" takeaway. Mahan has one of the best.
He uses his hands, arms and shoulders all at the same time to take his club away from the ball. If you watch his setup you will see a triangle formed between his shoulders and his arms. Now as he takes the club back pay special attention to how long his triangle stays intact. This is how he maintains such a great rhythm.
If you want to smooth out your takeaway then try to copy Mahan's. The added benefit is that if you set up properly then it is very easy to get your club on the right path with this technique.