It's definitely an evolution of the three-click mechanic - It uses the bar to tell you the power of your swing. You basically set up your shot, and then motion your Wii remote down as if you're going to swing. You can then hold B for a practice swing, or hold A to take the shot. When you take the shot, there's two markers - a wii remote marker, and a character club marker. The more you pull back and angle the wii remote up, the more power you will have in your shot.
So you move your Wii remote back and then you have to pause and hold that position, and the character's club icon will catch up and mimic what you just did. When it reaches that point in the bar that you've paused at, the character's swing will start, and when the character club goes left to the icon quickly, you need to swing your Wii remote at exactly the right time to make a good impact so it doesn't slice or draw. Throughout the swing, you have control of slices and draws, too, by twisting your Wii remote and holding it through the swing.
The only problem I have with it is that it feels kind of funny and unintuitive when you stand to the side with your foot forward - but there's a brief camera moment that looks in the character's perspective at the ball, which helps. Also, it kind of poo-poos over the whole golf mentality of "keeping your head down".
But it's still fun and satisfying.
Putting is the same way, too, but some douches with gaming industry blogs went and said it was too hard, and now it's tuned so that it's really hard to miss.
