Lets see, little ARM CPU...so there goes performance....
Productivity, pretty much anything you can do on an iPad can be done better on a Net book or Laptop, or desktop if you dont need to be portable.
You bash the performance of ARM processors then you bring up netbooks? Netbooks typically run ATOM processors. These may in some areas have some slight advantages over an ARM processor, but in real world use they are at a serious disadvantage. Why? Because most modern x86 applications are designed with much more powerful processors in mind. In contrast apps designed for ARM devices are optimized for these processors.
Also netbooks screens are far too small to practically run multiple applications side by side.