Let's look at the various angles and see how things stack up:
- As a business/work machine
You can bluetooth or use the external port to attach a keyboard, but you'll have to switch between typing and touching to interact with the screen. This will get old (and tiresome) quickly. Traditional laptops have the keyboard and mouse within easy reach so the transition is smooth. This... not so much. Also, as I understand it, this does not support multitasking. If that's true, then that effectively torpedoes the productivity aspect of this tablet.
- As a music player
You'll want to use headphones with it, but it'll be cumbersome to place next to you while working, or anything else for that matter. The iPod works because of its unobtrusive form factor. It's a "go anywhere" type device, unlike the iPad.
- As an Ebook reader
Apple might be on to something. E-ink is very easy on the eyes, but is currently only monochrome and has a hideously low refresh rate. LCD screens cause significantly more eye strain, and are harder to use outside where ambient light is strong, but have color support and good refresh rates. Comic book fans might like this.
- As a media player (other than music)
Good idea, but gimping the storage capacity is a bad idea. 16-64 gigs of video goes bye bye in a hurry, and you'll be paying a $200 adder to get to 64. This could work for watching a few episodes here and there, or SD streaming content, but it won't replace the need for a good HTPC.
- As a gaming device
Virtual buttons = fail. Good control schemes are hard to find in iPhone games, and this will carry over to the iPad.
- Casual net browsing
This is probably the best application of the device. The touchscreen should make the experience pretty smooth. The lack of Flash support out of the box is gonna suck on occasion.