Althought, I've not bought an iPad, I would say you can't just live with an iPad. You do need a regular computer, for instance you need a computer to activate it/ update it etc. Also, comparing iPad to Netbooks is like comparing apples to oranges ( no puns).

While iPad may not be a replacement for a notebook/netbook, netbooks are not worth owning. Based on your usage, iPad may be a good idea as it can do all those things you've listed. Since you have used Macbook in the past, have you considered Macbook Air ?