Got one of these for Christmas and have been using it intensively since. To cut to the chase, it's a terrific little machine and I have no hesitation in recommending it to anyone who wants a good personal PC and is prepared to work with relatively little onboard storage.
Positives:
looks great, nice finish, build feels very solid and classy despite being so light, keyboard and buttons very professional - everyone who has seen it wants one.
screen brightness and usability good
battery life seems to be around five hours - the best I've had from any laptop or notebook.
responsiveness excellent - it just feels fast, and I'm told a cheap and easy memory upgrade makes it faster still.
wi-fi access seems particularly good too - I can go from cold to online and working in less than a minute. Compared to the Dell laptop with Vista I bought a year ago, (which runs like a donkey with two broken legs no matter what I do to it) this is fantastic.
Negatives:
everything is good but there's no getting away from the fact that it is also small. This is a fabulous machine for working on trains, planes, the back of taxis, especially for quick internet access and emails and so on. But you wouldn't want to be squinting at it all day and you wouldn't want to write a novel on this keyboard, not unless you have the dearest little pixey fingers. However: plug it into a keyboard (I'm writing this on a nice basic Logitech keyboard which cost me all of £14) and a monitor and you won't know the difference. In fact, from this point of view it's better than a standard notebook as it takes up so little deskspace.
there's not a lot of storage for documents and programs and as others have said, the way the storage is organised doesn't help. However, you can add onboard storage as easily as inserting an SD card (I immediately added 16gb at a cost of around £20), you can very easily tweak the way storage is used so that your documents and programs automatically go to the largest storage area (much simpler than I'm probably making it sound) and you can get into the habit of using external storage for stuff you're not using every day - I have mine connected to a big 250gb Maxtor drive. Personally, I find that more and more of the stuff I do is web-based anyway, from Google mail and Docs to Flickr and Blogger, so the problem is starting to disappear.
In conclusion, if you're prepared to work around its natural limitations, a great, truly portable personal notebook. I never thought I'd say this about a PC, but I'm very nearly starting to feel some affection for it!