The benefits of an iPad are simple.
It's portable.
The battery lasts a lot longer than most laptops, so you aren't tied to an electrical socket, as long as you can charge it from time to time.
Can be locked to one specific app (handy if you buy the iPad to use a specific app).
Easy to use.
The downsides:
It has a virtual keyboard. This is important if you do a lot of typing. I would at least recommend you use an iPad with an external keyboard.
The apps are not as powerful as the full applications in all cases. For instance, while the MS office apps are perfectly usable for basic document editing, they lack the full features of the office suite on the Mac or PC.
They aren't as powerful as PCs or Macs with the equivalent prices. This doesn't matter for most people, but it might..