You can do a lot on them but you mostly do need an Internet connection. Documents and spreadsheets easy. Photo editing and storage again easy through various sites even simple video editing. Email obviously and a whole load of other stuff. If your in the middle of nowhere though and no Internet your options are cut down. Big pluses are amazing battery life, from completely off to running in around 15 seconds. Very long hardware life. And something that is light weight to carry around.
I didn't think much off them and then was tasked to look at them for work. I changed my mind about them and we are about to buy 40 or so. They suit what we do quite well especially since we are moving our stuff over to Google apps. Might not be so useful to you though depending in what your after.
Oh they will work with the new GS911 as well if that is of interest.