The MBA is a performer in the terms of Ultraportables.
Most ultraportables are using ULV CPUs. They're in the 1.2/1.4 GHz range. So what if they have two or three ports or weigh a pound less. Most have smaller displays and sometimes non full-sized keyboards.
The whole point of the MBA is it's powerful enough to be a primary Mac. It doesn't have an inferior display and the display is full size. The keyboard isn't cramped. The Nvidia GPU, paired with a full Intel Core 2 Duo CPU at 2.13 GHz, and SSD leads to a faster than normal computer for the average Mac user. At the same time, it looks gorgeous, and the aluminum perfectly dissipates heat too.
I don't want an ultraportable if it cannot be my primary Mac. If Apple puts an Ultra Low Voltage CPU running at 1.4 GHz in the MBA, uses Intel integrated graphics, and reduces its weight with carbon fiber, the MBA will be useless to me. I don't want to sacrifice power. I don't want a secondary Mac. I don't want to lose performance and beauty and size. I want to carry around something the size of a few magazines that also performs like a full blown Mac.
That is what the MBA is, a PRIMARY MAC CAPABLE ULTRAPORTABLE! I will be done with it the day Apple sacrifices power to reduce weight, because that will reduce the end user experience.
The MBA is not so much an ultraportable as it is an executive/business class Mac. It is the envy of executives, consultants, salespeople, businespeople, grad students, lawyers, and etc... because it's fully capable of being their sole Mac. It drives up to a 30" ACD while at their desk... a true ultraportable runs Windows and only works as a secondary advanced netbook. The MBA is a super lightweight notebook that wins over the ultraportable market too.