I have an ipod touch, and it's simply the best thing i've ever bought. The only problem with it, is... it's too small ! Trying to look at oOple on it can hurt your eyes, as for composing messages and e-mails, it works, but a bigger screen is what's needed.
I guess a lot of people felt this way, hence the ipad. For quick surfing, e-mails etc it's going to be ace. If the price is low enough, it will sell well.
I have 'remote' set up on my ipod (it's a free app that allows you to browse and control your mac or apple tv over wireless) for wireless audio playback, and it's great. I can listen to and browse all my music wirelessly on the touch and listen to it all though the hi-fi.
It's all the little apps like this that make stuff like the touch / ipad (hopefully) such a nice user experience, one that shouldn't be knocked till you've tried it
The ipad will also be the ultimate portfolio tool for designers, imagine showing your work to a client on that and flipping between stills and video - nice.