We have both a netbook (2yrs old) and an iPad2.
The netbook only gets used these days for playing video files on the TV. It wasn't as good as a full size laptop and battery life isn't that great.
The iPad, battery life is good, it's comfortable to use on your lap while sat on the sofa or in bed. Good for browsing the internet, Facebook, checking email (although writing email isn't great), great for the apps like BBC iPlayer, Amazon shop, games, etc.
But the downside is typing. You can't seriously type on it. Forget emails or documents, no chance as the on screen keyboard is rubbish for any typing beyond a 1 line email.
Also you can't print from an iPad unless you have a brand new AirPrint capable printer and there are only a few of those.
It's a personal thing though and depends what you want it for.
My wife uses the iPad all the time cos she only wants to browse the internet and Facebook, but I prefer a fully functioning laptop.