I picked up one of these on an impulse when it was on sale at Best Buy.
The form factor is great. I was already on the lookout for a tiny sub drive like this. Though it might be so small to get lost easily. Fortunately it comes with a soft rubber case to bluk it up a little while in your pocket. The build is nice to. It feels really solid. Even if it gets stepped on, it'll last.
As far as tecnical performance, however, I can't say it's all that great. Write speeds are horrible* (100MB file, sustained write speed of around 1.1 to 1.2MB/s... and yes, that's on a USB 2 port). It chokes even more if copying a folder of several files. Right now I'm looking at a 15 minute wait to copy a folder of 700 items at 105.3MB total size. That's just not right (no pun intended).
So, for style points, it's great. For technical performance, I can't recommend it.
*These particular tests were performed on Mac OS (both Intel and PPC, Tiger and Leopard), though similar performance occured on Windows boxes (XP, no compression software).