I also don't like an app that has the kid shake the iPad (or iPhone) a lot.
I'm torn on the "Don't trick my kids into buying stuff" one. I've seen a lot of crappy apps (and even well-built Smurfy-Smurf ones) that are just funnels to in-app purchases. But I've also seen parents leave outraged reviews because a developer dares to have in-app purchases for additional content in his free app. Or they turn their nose up at paying $1.99 for an iPad app. The world doesn't owe you free high-quality kids' apps. Go ahead and funnel your kid's allowance into iTunes credit now and use it to get them to clean their room.