DD9 got her palate expander in March 07 when she was 8. Braces on the 2 front teeth and 2 permanent molars to start, and they bracketed the other 2 front teeth when they came down far enough to be included. The RPE came out last month, so she had it for 11 months.
In this phase, the ortho fixed her crossbite and her front teeth will be nicely aligned where they are supposed to be. He cautioned us that this does not mean we won't need another phase of braces later, but we have at least reduced the chances of that as well as reducing the chance of having to extract permanent teeth.
I know there are two camps regarding Phase I. If you look, you can find enough research to support your opinion no matter which side you are on. My feeling is this... when they kids are still growing, you can guide the teeth into place as they come in. If you wait for the jaw growth to stop, you are then moving teeth that already know where they want to be. As bones harden and teeth have their place within those bones, you are causing more pain and trauma by moving them at that point. Moving the teeth of a younger child with softer bones, putting those teeth where they belong, and allowing the bones to harden as the child grows is less painful.
My then 14 year old babysitter had an RPE and said it was horrible each and every time they had to turn it. My daughter didn't need painkillers to turn the RPE, has had very little tenderness after adjustments, and has more self confidence because her front teeth are straight.