The form factor, and the weight, they experimented with widely. I've seen tiny Smart Displays; huge (REALLY HUGE!) ones, and several inbetween.

They were OK, I guess, but as peter Garner says, they need to be useful.

The trouble with the Microsoft design was that it was only a display. If the wireless went down, or you moved into the sitting room where the signal was poor, or you wanted to take the thing next door, it simply died. It didn't work at all.

As Peter says /m3 even a Palm Pilot chip inside, and it would have been useful.

Of course, then you'd have wondered why it cost so much...