Tomborg:
so if the meter is not linear, how do we understand and use it?
I'm afraid that's where experience comes into play, from my point of view anyway. I play this game purely by feel, I don't use any percentages and honestly couldn't tell you how far a 4 iron hit with 85% power will go. I just move the marker, drag the power meter to what looks about right and go for it.
I know this isn't very helpful but I think playing the game by the seat of your pants is a lot more fun.
My advice would be to not get too bogged down in numbers, just play the game and you'll develop a feel for the shots.