The later VGN-U were, at their release, the smallest independent computers running Windows XP and the most powerful high-end subnotebooks at the time.
Battery life of the Pentium-M series is said to be anywhere from 30 to 45 minutes over the Celeron-M model as a result of having SpeedStep.
The internal display is a custom transflective panel made by Sony with a resolution of 800x600 pixels.
Connecting an external monitor to the VGA port of the docking station enables a maximum resolution of 1600x1200x16m.
With updated drivers from Intel, the ability to rotate the screen in 90, 180 and 270 degree modes is enabled.
The display is very small, roughly 5 inches (127 mm) diagonal; it may cause some eyestrain if used for prolonged periods.
Original U50 and U70p units had a faulty Synaptics driver which sometimes caused USB HID input device conflicts.
There are a couple extensions available to allow Windows Media Player and Winamp to display output to the controller unit.
The iGo Juice and other third party adapter manufacturers make power supplies that are compatible with the U series.
Users are advised to check voltage, current and power ratings to ensure compatibility.
There has been no report of modules larger than 512MB as of July 2024. i.Link is Sony's name for IEEE 1394; the port is compatible with 4 pin FireWire cables, and is unpowered.
Only drives compatible with this extended power jack are capable of booting CDs and DVDs on the U series.
(Note that the Sony DRX-510UL drive can be used to read/write discs once Windows has booted, but the red text halfway down the page says specifically, "The DRX-510UL cannot handle [i.e., be used for] system recovery (the reinstallation of the OS).")
The upgraded features include a 1.1 GHz CPU with 2 MB of cache, and a 30 GB hard drive.
In Hong Kong, Singapore, and a few other south Asian countries, Sony had introduced a regional localized model, the VGN-U8G and VGN-U8C.