I started out on a 12" 867 mhz, and upgraded to a 1.5 12". I eventually traded it in on a dual g5 powermac because I wasn't on the road so often, and wanted the extra power for handbrake, virtual pc and the like.
They were both good, sweet solid little machines, perfect for light browsing, word processing around the house, etc. My dad recently bought a 12" ibook, and while I had it at the house upgrading tiger, I forgot how much I missed that form factor.
Is it just me, or would Apple have sold a s#^%load of machines with the 12" form factor? I can't believe Apple didn't make the Air into a similar shape. Could you imagine how light and portable that would have been?