It doesn’t take up anymore space than the iPad, that keyboard is the cover so it can be configured to be out of the way, it’s a 10” tablet the RT version is thinner and weighs roughly the same as the iPad.
The Pro version does not use a 140 watt chipset. In fact the i5 being used draws less than 17 watts. Built around the ultrabook platform which draws very little power.
Where are you getting your FUD?
The i7 chipset I got from a tech review; which seemed outrageous amounts of power for a portable device. This site is claiming 42 Watts; which is still incredably high.