Is aluminum vs. white/black that big of a deal? And if you want the graphics card, is 15" vs. 13.3" that big of a deal?
As to the first question: Er, yeah. The MacBook might be fine for students and slackers, but for grown-ups and professionals it looks a bit cheap and tacky (no offense).
As to the second question: Short answer, no. But what makes a bigger difference, portability-wise, is weight. The new MBA is nearly half as light as the alternatives. (That's one of the biggest drawbacks of the MB vs. MBP, btw -- while the MB is slightly smaller, it's just about as heavy as a MBP.)
As for the overall question, looking at it from my perspective, I'm really torn. And I suspect I'm not alone.
I was looking forward to what Jobs would whip up for MacWorld, holding back on my purchase of a new laptop (still using a PowerBook G4) until then.
I'm thrilled with the overall form factor. What I'm not so thrilled with are:
1. Price. The minimum, imho, is $2099, not $1799, since it only makes sense to get the 1.8 MHz customize option to extend the life of your MBA. I don't know why anybody would not opt for that. And when you're spending that kind of money, it's hard not to notice what else you could get with the same amount, or how much you could save by picking up a MB instead -- and with more power, etc.
2. USB. At first the idea of only one USB port didn't bother me, until I realized that I like to use a mouse with my PB. Which means that my MBA's port will be filled most of the time with the mouse receiver. One extra USB port doesn't seem like too much to ask for. (Jobs' vision of a wireless world is inspiring and all, but in my real-life experience utopia just ain't here yet.)
3. Hard drive. I don't mind the limited memory space. What I'm concerned about is the speed of the thing. I'm no expert, but I hear that it would be pretty slow. (Not the SSD, of course, which I'd love, but it's just way too expensive right now.
So... I'm thinking that maybe I'll wait some more. What will I be waiting for?
1. The next MBA revision. Maybe by then SSD prices will have come down to a reasonable level. Maybe other aspects will be improved (additional port, etc.).
2. The next MB revision. What I'm really curious about, however, is what will the next MB revision look like. Will Apple keep encasing them in plastic? Somehow I doubt that. Also, what will it do for the MB based on what it will have learned from the MBA experience? According to our trusty Buyer's Guide, they're due for a revision in about four months. Can I wait that long? Probably.
Ultimately, I'm waiting to get my hands on a demo model of the MBA to make my final decision.