It doesn't support Flash,
It can't make phone calls.
It has no USB ports.
It has no memory card slots, or camera.

While AT&T is saying it will have unlimited data download for US$29.95 per month, there are arguments being made that AT&T does not have network to support it.
$630 for the AT&T version
I guess you can't multitask. You can't have a browser and a word document open at the same time, for example.
I am sure there are plenty of things I don't understand about it, pro and con. I do wish it, or something like it, would be a success.

It almost seems poorly thought out. Maybe this is the first try.

Indeed. http://www.silentpcreview.com/forums/vi ... hp?t=57335

Cheers!