Full size to me means separate cursor block, numpad and a key travel of more than a few mm. I am probably more partial to the keyboard I'm using than to any other aspect of my computer.
I remember a number of times being attracted to the ultra-portable Fujitsus and Sonys of the world a few years ago and being totally unable to type effectively on them because the keys were so close together that my fingers kept getting in the way of each other when typing.
Personally, I loved the keyboard on my T23 Thinkpad.