Earlier quoted context omitted.
it's better at most non-geeky things than your macbook pro. i know because i own both.
Is it $500 better? Compare a Macbook Pro to another laptop that is $500 cheaper. I'd argue there is $500 worth of value there. Is there $500 worth of value for the iPad over the Macbook Pro? I can think of a lot of things to do with $500 that would be better for me than buying an iPad.
IMO, the best option for most people is to buy a cheap 17" laptop and an iPad. And for gamers a desktop + iPad is much more reasonable than a "gaming" laptop.
PS: When you consider how often the average users system is down (software/hardware/virus etc) having a simple independent device that lets them use email and most webpages is a huge advantage relative to spending 500$ for a better version on the same basic HW.