My iPad regularly travels up and down to London with me for my course...I use it to access the library catalogue, send emails and read my set texts. There is a great APP called Good Reader which allows you to annotate articles etc with highlighter, notes etc just like a paper copy, and without it I would be weighed down with papers. I use the notes APP to make notes of books I need to get, but I don't tend to use word processing as such, though I do have Pages (iWork) on it so can access documents I have written and I do sometimes make minor changes..it's not that you can't do it, just I prefer my iMac for that. I am on EPE with it now.
I would say if your primary requirement is word processing, get a laptop. But for everything else, this is the business.