I believe that a portable computer has utility as a portable only if one is inclined to carry it (and thereby use it), else it is an expensive desktop replacement.
A netbook is supposed to be an ultra low cost computer primarily for Internet activities and as such has minimal specs and is compact and lightweight.
I prefer an iPhone since it is there with me, even if I did not plan to carry a netbook, camera or maps. A netbook needs booting up, is not convenient and looks weird to use while walking, whereas I don’t hesitate to use the iPhone to lookup yellow pages, train timetables or walking/driving directions.
The features a gadget has are important only to a degree, beyond that it is the utility derived from it on an ongoing basis. That is where I find the iPhone to be the most valuable.