Joy of a thirty day owner - I got my i5/256GB on release day, June 20, directly from Microsoft. After the last two updates, battery drain and WiFi connectivity are resolved, and it has truly become the best piece of hardware I have purchased (going back to my first laptop in 1986 - a Toshiba T1100 Plus). It is so good, in fact, that it survived the 30 day return period and is now a permanent part of my computing life (those of you who know me from other forums a LOL because no computer ahs survived that 30 day torture test since the release of Windows 8). For me, it is the perfect (and lightest, thinnest, most powerful) ultrabook, and does double duty replacing my iPad as my go to tablet.
Like others around here, I agonized over whether to switch it out for an i7/512GB beast. Although the 512GB is tempting, there is NO WAY to justify the $650 difference unless you deal with large VM's; edit tons of RAW photos; or keep massive databases on your computer. Thanks to a $99 128GB SanDisk mSDXC, I have a 384GB pool of data storage, supplemented by my 1TB OneDrive attached to my Office 365 Home Premium subscription (in fact, I have 2TB available, because we are only using 4 of the 5 subscriptions at present - Ed Bott even suggested getting the family plan and creating a set of five 1TB "drives" in the cloud for your personal data).