Hard to make that statement when I'm running my MacBook Air like a heavy use computer. Folding@home, Multiple VMs at once (Usually 2x Windows Server 2008 + Windows XP on top of OS X), Handbrake converting. Runs like a charm, requires reboot every 2 days to clear the swap file from getting too big but no problems at all.
But certainly you must admit that 2GB of RAM shared between three OSes isn't ideal? I would love to run Windows 7 on my MBA within a virtual machine like Parallels or Fusion, but I cannot stand 1GB RAM on OS X and 1GB RAM on Win 7. For that reason, I use Windows 7 in Boot Camp to keep 2GB on the main OS I am using.
I believe the biggest problem/limitation of the MBA is the 2GB of RAM. If we counted all the people who have stated "if the MBA had 4GB of RAM I would buy one," I am sure Apple could triple the MBA's sales. Surely Apple knows this is a problem, yet it hasn't provided more RAM even as an option in the MBA.
I would say that your experience of running three OSes surely isn't "typical" even though you're using it successfully.
Obviously, the port selection hurts it somewhat, but I think it's fine for the non professional to do graphics editing. I am not talking advanced stuff, but advanced work required by a production studio isn't being accomplished on a MBP either... it requires a Mac Pro for the most part.
I definitely don't believe the iPad will eliminate the need/demand for the MacBook Air. In fact, I see a growing market for the MBA as more and more people are willing to pay $1500 for a 3lb ultraportable that has the capabilities of the MB. The MBA essentially offered the same performance as MB when it was introduced with the updated Penryn CPU and Nvidia GPU in October 2008. Unfortunately, Apple hasn't truly addressed the MBA's capabilities since October 2008. I do expect an update within the next six weeks for sure.
I would like 4 GB of RAM first and foremost. My second concern is the drive space and SSD performance, as I want a larger SSD that is as fast as the Runcore SSD. The other thing I really want is the glass trackpad; I totally agree with others who really want this in the MBA. The "silky smooth" glass buttonless trackpad is another simple upgrade, that costs almost nothing to make, but substantially adds to the user's experience.
I can live without any other upgrades. The MBA is thin and lightweight enough - it's the perfect size and weight offering a full sized keyboard and 13" LED display. An Arrandale CPU would be nice if it also means a dedicated ATI graphics solution. USB 3.0 would be nice since there's only one port. Aluminum capped keys seems like the feature that could further the experience and feel but I doubt that would happen. I don't need a glass cover for the display. I could use less space around bezel and keyboard, but it's not necessary. All in all, the MBA is still perfection in the look and feel. We are all so lucky, Apple chooses to compete in the ultraportable notebook market.