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They all go by "specs", but only by specs that can easily be turned into numbers that can be compared. The trackpad quality cannot be turned into a number. So if some designer, or some engineer, comes up with an idea how to improve the trackpad, they'll be asked "how does that increase our specs", and the idea is shot down immediately.

Lame argument. Your assumption is that PC manufacturers only care about specs and nothing else. This isn't true, specially when you get into the high end $1000+ market where people expect quality from their machines as well as speed.

Plus it's selective and overly biased. I can say the Zenbook has an advantage over the MBA because it uses a higher resolution IPS screen, and you can toss it back to me as nothing more than a useless spec advantage and doesn't do anything to change the near mythical "user experience". Whereas if the situation were reversed, you'd claim it's due to Apple's commitment to using the best parts.

And there's the fact that Apple fans claim not to care about specs...until they do. I mean how many people here have proudly boasted about the iDevices having the best GPU performance in the mobile scene, and love posting benchmarks stating as much. I'll tell you: tons. Things will remain this way until Apple falls behind on that front, then it's back to the good old "specs don't matter" arguments.

The truth is build quality, user experience, and specs all matter. They all form a cohesive whole that makes a machine worth having. Right now, none of the ultrabooks offer the entire package. With the MBA, I get access to a large amount of very useful gestures and smooth controls at the cost of having it coupled to a rather middling display. With the Zenbook, I get an excellent display at the cost of having a merely functional trackpad. No matter which one I get, I'm losing out on something I'd like to have.

...though if it makes you feel better, I'm currently leaning a little more towards the MBA.
 
I'm a windows user very interested in this laptop, but my concern is that it does not come with Mavericks. Would this be something I will have to pay additional for when it ships, or is it a free update?

If Mavericks comes out within 30 days after you have bought your MBA, you will be eligible to download it for free.
This happend with me with Lion to Mountain Lion when I bought my MBP.

If Mavericks is released 31+ days after you have bought your MBA, it will cost you around $20 or €19 to download from the App Store.

Here's the extra bonus: You can install Mavericks onto 5 different macs (MBA, MBP, iMac...) if they are connected to your iTunes/App Store account.

In my case, I got my iMac with Snow Leopard, didn't upgrade to Lion.
Then I bought my MBP with Lion, got the free update to Mountain Lion for that one and updated also my iMac to Mountain Lion.
 
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