The HP Portable Hard Drive, while indeed quite portable, is a mild oxymoron: it wants to remain plugged in all the time.
And that's not because it's heavy or bulky--it's not--but because its built-in SimpleSave backup software is designed to automatically make backups only when the connected computer has been idle for 5 minutes or so. In other words, the drive works best when you plug it in, run the backup software, and forget about it. Now that seems more suitable for a bulky desktop external hard drive than for a compact device that's designed to be mobile.
It would have made more sense for the backup software to run automatically each time the drive is plugged in, similar to the Clickfree C2N or C6, or even the previous version of the drive that was called HP SimpleSave. Maybe this will be added via a software update.
Other than that, the new HP Portable Hard Drive is very similar to the HP SimpleSave of a few years ago, with two big exceptions: it now offers up to 1TB of storage space (as opposed to just 500GB) and USB 3.0 (as opposed to just USB 2.0). The SimpleSave backup software works similarly: once launched, it automatically searches the entire drive for data files, such as documents, photos, music, and videos, and backs them up on the external storage drive without any user interaction.
The backup software doesn't provide many options that would change how it works. All you can do is change what type of files it backs up and what folder it looks for them in, nothing else. You can't even make SimpleSave back up a specific folder or schedule a backup job at a certain time. However, if you just want to make sure your documents are backed up, the default settings will take care of the job. Again, just plug it in, run the SimpleSave software stored on the drive, and don't unplug it from the computer.
To make up for the somewhat rigid backup software, the HP Portable Hard Drive is affordable, with the 1TB version costing just around $90 on the street. You can also find the 750GB and 500GB versions of the drive for around $85 and $80, respectively.
To find out more about its performance, check out CNET's full review of the HP Portable Hard Drive.