This is probably in my opinion one of the most useful machines for a true road warrior looking for the ultimate in mobility. I've been using PC and Mac portables for a while now and have 30+ years experience with computers and this is, as of yet, the most useful device for mobile work that I've come across. That being said there are a few constraints a buyer should be aware of beforehand.First of all: the screen. It's small (only 11.6") and resolution is a relatively standard 1366x768. This means that if you are often reading documents and articles, gathering information over the web or editing photos you will definitely feel limited by the smaller size of the screen. (This is NOT a computer for people with poor eyesight.) Another small thing to consider is that this screen has a 16:9 aspect ratio. Some older mac apps are designed for Macs using 16:10 screens meaning that some dialogue boxes were designed for a minimum vertical resolution of 800 pixels. Occasionally you may encounter an app with dialogue boxes that partially run off the screen when they are displayed on the MacBook Air 11. Minor niggle but worth mentioning since it's annoying when/if it happens. Otherwise the screen quality, brightness etc is great for web surfing, writing e-mails, watching movies etc.Second: the keyboard. It's also small. Not that I mind it much since I have relatively small hands but if you have larger hands you might want to consider the 13" version, sacrificing some portability for a little bit more space for your hands and wrists. If you have particularly large hands you might even find that you rest the bottom of your palms on the razor thin front edge of the unit making extensive typing an uncomfortable experience. As I said, it's not a problem for me but make sure that you try out the keyboard before you buy this machine. Otherwise the keyboard quality is great, with backlighting and no flex or creakiness at all.Third: the track pad. In order to accommodate the keyboard it's quite small, vertically, compared to the track pad on a MacBook Pro 13 or a 13 inch MacBook Air. If you are used to the huge glassy track pads on larger macs you might find that you occasionally encounter the upper or lower edges of the track pad when scrolling, pinching or moving the cursor from edge to edge on the screen. This, again, is no big issue for me and just took a bit of time getting used to. Not a major hindrance in my book but if the track pad is important to you then you might want to consider the 13 inch version.Just keep these three potential comfort issues, or minor niggles if you will, in mind and make sure you take a look (and feel) at a physical device before you make your purchase decision. Remember that this is probably not a machine for everyone, and definitely not the ideal primary machine for everyone, but if you don't mind the size constraints (after all, this machine was designed to be the ultimate ultraportable) it will probably be one of your best computer purchases all year.Also, do make sure you get the version with 4 GB RAM (as opposed to the baseline of 2 GB) as RAM is non-expandable on the MacBook Airs. You're basically stuck with whatever RAM your unit originally came with. When you install future O/S upgrades (or open a bunch of tabs in your web browser) you will probably appreciate splashing out the extra money for a larger amount of RAM.