Working out where the ball will go on it's rebound is relatively complicated, and is sure to get them thinking in a physics-y maths kind of way. Peggle will also teach them (and you) about perseverance.
Nothing. At all. Unless you don't like unicorns and rainbows.
Peggle does have multiplayer - although it's only a competitive, see-who-can-get-the-best-score game. Still, maintaining the series' "one more go" mentality, it's bound to keep you playing for a while...
Disclaimer/disclosure: Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product. Links to Amazon are affiliate links, and we will receive a small fee should you choose to complete the purchase using these links. This doesn't affect the price you pay for your product.