It is, as Apple touts it, a 'pocket computer'. That title adds much more weight to its functionality, though we have been using to it check emails, read news, play games, listen to music, take notes, ... all this while.
I love it because it is the first Christmas gift in recent memory that my kids have played with every day since December 25th. It is so much more than the mp3 player I thought I was buying.
I hate it because since 12/25 I have bought 2 iPhone 4's, an iPad 2, a 13" MacBook Pro and am considering a new iMac.