I have this notebook for nearly 2 years. On the performance side there is nothing to comment on, works really nice, fast CPU and the SSD also helps. However in terms of build, it is the by far the most problematic gadget I have: I used this laptop mainly while traveling (used because even though I still have it, I don't use this anymore, changed to a Surface that works great). Usuall  I was traveling once a week, so you can imagine the laptop wasn't used much. Yet, after several months the laptop turned off while working on it and couldn't get it back on. As it turns out the motherboard had a failure and the service changed it. When it came back, the laptop was not working without staying plugged in. Sent it back to the service and when returned and they had it fixed. To my surprise that the battery was not holding on anymore - at around 35%-50% of battery, the laptop was turning off. I sent it back again, and they said by that time the battery was not in warranty anymore and it costs 120 euro to get it changed. I didn't feel it was right as this drop was all of a sudden, and I also didn't use the laptop that much to explain the battery failure so soon. So I rejected and since I haven't used the laptop because I didn't want to spend money anymore on such a device that breaks so fast. This was also a poor service experience, not only of the product. One other thing that created problems - the protection grill on the vents on the bottom of this laptop breaks easily without doing anything, and I wouldn't be surprised that because of them the motherboard broke if they went on the circuits there.

Performance is not everything although is important, but the way this laptop has been breaking down on me, I would honestly not recommend it to anyone, and be very careful of Asus products (they might look nice and come at good price, but you may end up paying more in the long run)

I purchased Asus Zenbook UX31A, i agree it's beautifully designed but after a while the power button doesn't power the damn book up again, i have to press multiple times before i get the book to power on. I called Asus support and that is the worst support ever, first the guy that attended to me was very sluggish and kept asking me the same question over and over again. i got so irritated and drop the phone, then i called back spoke to another support rep which turn out to be the same as the first one but i decided to go through with the support call until the end. My ultrabook is still not fixed and i would not recommend this to anyone. When buying ultrabook we need performance rather than aesthetics in notebooks.
Ralph

All this looks nice on the paper but in my heavy user practice came very unpleasing shortfalls to light: 1 the UEFI as for now is a really hardness for a dual boot operation 2) the 128GB is just small for the Ws monster with the restore points recovery part. etc. eating up tens of gigs quickly 3 the adapters to use don't work well if at all, especially the micro hdmi is a nightmare. So I quickly decided to replace this nice toy.

I just got the i5/128gb version from the MS store on sale.  You are sure right about the fan noise under heavy load (installing a slew of Windows updates).  It's like what a plane sounds like taxiing to the runway and just at the moment it accelerates to start for takeoff, including with the high-pitched whine.  Aside from that, this is a nifty laptop.  But had I know, I might have opted for the 31A.

According to the Asus U.S. website, the UX21A comes with either the HD 1366x768 or the IPS 1920x1080 display.  With the latter, other reviews have noted the need to use zoom to read text.  For many people, that's a problem with 1920x1080 screens of any size - I use a 1920x1200 - but it's accentuated on a small laptop.  In addition, Asus's website shows this model with either an i5 or i7 CPU.  That's what the website says.  Although the Microsoft Store is currently selling the i5/HD version at a substantial discount, it's to be seen what actually shows up in more widely.

face it, the keyboard on these laptops isnt even close to the rankings you give it, there in fact terrible compared to something like the lenovo X1C

Great review.
please review New Asus Zenbook U500 ( with Nvidia 650M) as soon as you get your hands on . I'm very looking forward to it .
thanks in advance