I think pretty people have clear advantages, although the importance of it depends on a few things.
First of all if you're a boy or a girl, man or woman. When it comes to intimate relationships, for example, I think men place a slightly higher value on finding someone physically attractive, whereas women are more likely to use other measures of success. Physical attractiveness can be a powerful tool for anyone, but especially for the fairer sex. Whether this is in the process of changing now, is of course hard to say.
In any case, seeing physical attractiveness as a tool is probably the key to understanding it. Attractiveness in itself can't make you successful, just like a hammer can't make you successful. You actually have to pick it up and use it - and use it for a specific purpose - which, in turn, requires some underlying intelligence and motivation.
But keeping everything else equal (intelligence, environment etc.), yes, pretty people have "better" lives, in the sense that they have higher social status. This will be determined from an early age. How parents treat attractive children compared to unattractive children is one thing, but what may be more important is how
children treat attractive children. I think it's fairly safe to say they treat them better, which leads to an upward spiral of social confidence. Not genuine confidence, perhaps, but an increased confidence in their ability to assert themselves socially.
And I agree with what the other people said about it depending on what you want to do. Just like a hammer isn't good for typing on a keyboard, good looks in itself isn't what you need to write a composition. But if you want to perform that composition on TV, then suddenly you'll find it useful to have a pretty face.
I also think the importance of attractiveness depends on who you're talking to. To a ten-year-old it could be extremely important. On the other hand, to a forty-year-old it may not be as important, simply because s/he's learned what other factors to look for.