I'll disagree with HC that tablets are meant to be toys, although there is a lot of quick, fun gaming to be had.
For me, the tablet allows me to do lots of things that I would normally have to sit down at a computer to do, some of which is surfing and checking email.
My tablets will never completely replace my computers, but they do allow me to do lots of things untethered from my computers, which is fine with me since I spend all day with them already.