This was the book that introduced me to the idea of synaesthesia, and I admit I loved it. While I agree that there was some over-dramatization, I can easily see a child having this problem-- not everyone is just ok with being labeled "different," particularly if it causes them trouble in school. And since the condition is so little-known, I can definitely see a child being ridiculed for insisting on the way she "sees" things.

I think that synaesthesia comes in a wide range, and can be everything from a definite asset to a disability (commanderd, for example, experiences tastes when she sees colors, and can find the wrong piece of artwork not only distracting but actually nausea-inducing). Most often, I suspect it's a little of both-- an oddity that helps out with memory but may make certain things confusing.