That's a great question! Most of Apple's fan and technology "experts" as well as journalist worldwide are giving tons of opinions about iPad and in sum we can divide the whole into three main groups: those who love it, those who like it but think it could be improved and don't thing they are going to buy one, those who hate it. I can say I belong to none of those groups (but if I had to choose, I would choose the second one).
That was my sudden reply to my girlfriend's question. I will try to explain this as we proced in the conversation.
As I first said, I think this will be a great device in the future, not now!
But let's take a look at what we have and what we could have in the near future!
If iPad had the right technology you could add unlimited space using an external hard disk connected to it by Wi-Fi, Bluetooth or USB! One of them now can contain up to 2Tb or even more and is not bigger than an half an A4 paper sheet, so you can easily put it in a drawer... need more? In a drawer you can put 5 or maybe 10 of them! 10x2Tb = 20Tb = 20.000 Gb = unlimited space! In such a space you can store everything, even a library of every book ever written worldwide!
Printers can already be connected to Wi-Fi routers instead of directely to Pcs (see Apple's Passport and Time Capsule!), so even print is not a problem.
DVD... there will be no more DVDs or BlueRay Disk in a near future... I think they will all be replaced by something with an USB like connector, so if you have USB readers you have everything.
If iPad had an OS like Mac OSX instead of iPad OS you could do everything you can on a pc, just like it were a pc itself!
You are worried about touchscreen but it's not a problem at all! iPad can already be attached to a fisic keyboard, so if you want to write anything, you already can without warring about mistouching the screen! And you already can write documents using iWork!
You can add a webcam to it (and hopefully there will already be at this point there will be one in it).
You can use Skype, iChat, emails, surf the web, read books, etc, etc, etc...
Battery life is up to 10 hours, 5 times more than a normal notebook and a little more than a macbook (for which now is up to 7 hours!)
Need something more? 
Maybe I missed something and a lot more about you can discover it in the video pubblished by Apple on it's wesite (I'll attach it down here for you)
I truly believe that when iPad will have an Operating System just like a MacBook has, notebook and everything similar to them will be trashed immediatly! Even now there's nothing similar to an iPad!! 
What do you think about iPad and the future?