I bought this flash drive back in around 2006 or 2007, I then got the 16GB one a few years later. Both flash drives still work like brand new, and I'm currently using the 4GB one as a readyboost drive. I removed the U3 program from the 4GB drive, and kept it on the 16GB one, since I only have any documents stored on the 16GB drive.
I like a number of things about the U3 system, one is the default encryption, another the ability to run portable programs from the U3 launchpad, simply by creating a U3 app shortcut. My favourite feature is that once you no longer need the U3 package, you can simply remove it. Now you've removed the Windows limitation of the flash drive, since U3 launchpad only works on Windows.
Technology has come a long way with flash drives, and the great improvements have brought about better technology at lower prices. Ten years ago, I ppurchased two 32MB flash drives from dabs for £50. For the time, 32MB seemed a giant leep from the 1.44MB floppies, and indeed it was quite a leep at 30x capacity. At the current price of £25, there's been a 2000x increase in capacity in the last ten years. Now thats really quite impressive.
Looking at the 4GB flash drive from todays point of view, as supposed to the 2007 view, its beginning to appear more and more ancient. USB 2 is becomming a thing of the past, as USB 3 picks up pace in the affordable marketplace, and there are already many high capacity drives out there. I doubt there'll be much use for only 4GB in the next few years.
If I was writing this review in 2007, I'd recommend you buy this flash drive. Its an excellent flash drive, the value for money is great, the speed is good, but the capacity isn't so high for current standards, and U3 doesn't appear to have much of a future.