Yeah guys, this is it! That's the next big thing!
No one give a **** about getting text-, music- and weather-information on his wrist, such products wouldn't be used by the masses (as we see from Pebble and Samsung Smartwatches).
But a watch, that keeps (accurately) track of your health and fitness could be THE next thing everyone is using in 7 years from now.
The watch would only be a display with battery and sensors, everything else is done by the iPhone/iPad (except some basic functionality like displaying the Time and stuff).
With your iPhone/iPad/Mac you see your health stats (which have to be way more accurate than Nike and Jawbone wristbands) - you see how much you sleep, walk, your hearth rate and so on.
People will need some years to get comfortable with that, but in the end many people will use something like the iWatch (Samsung will copy it).
Apple could make the iWatch iPhone-only, but also make an Healthbook-App for Android and Windows Phone.
I bet they won't although they would sell way more iWatches with an Android-Healthbook-App than waiting for Samsung to bring out their own Galaxy-Fit-Watch.
I believe the iWatch is going to be great and people will certainly use it.
On the other hand i'm wary of having a WiFi-Bluetooth-Battery-thing on my wrist all the time, especially when sleeping. Could be that that reverses the health-benefits from the iWatch.