Not particularly - the iPad is a great entertainment device, but the times when I desperately need an ultraportable is when I'm traveling.
I just went and plonked down some money on a new 13" MBP and I also just got an iPad - but I still love my MBA.
In the past couple of years, I've flown ~500,000 miles around the world. As a consultant, I take my work laptop - which is a clunky ThinkPad - and I got myself the MBA only to be an additional, portable laptop.
There is no way in hell that the iPad can be a replacement for an MBA. Hell, Numbers and Keynote are a joke compared to Excel.
Plus, you cannot use a bluetooth keyboard when you're on a 13 hour plane ride, which pretty much invalidates the portability/flexibility of the iPad for anything other than consuming content.
The MBA is simply fantastic for travel. There is no comparison. The iPad is a toy and nothing more. The MBP is great if you don't mind lugging around the extra 2 lb around the world, but for some of us the 2lbs add up.
(Let's see -- my laptop bag now has my ThinkPad, MBA, iPad, chargers and travel adapters, sleep mask, ear plugs, medbox with everything from multivitamins and pepcid to special medications, earphones, business cards, privacy screens, pens, portfolio and notebook, external USB HDDs and thumb drives, GPS, VPN access cards, and sunglasses, emergency tie + cufflinks, emergency deodorant, emergency nutri bars, emergency tea and coffee -- and of course, my
handpresso).