Kensington Universal Travel Adapter with USB

It has been 4 years since I purchased the Kensington universal travel adapter from Amazon.com and I am glad that it has survived all the international travelling and sockets over the years. For $29.99, it performed to its expectations and standards. Now, with so many electrical devices offering USB charge support, I am tempted to get myself another universal travel adapter from Kensington - a newer version with a female USB port. This would allow me to plug in the general USB cable and charge my electrical devices from the power outlet around the world - extremely convenient. I see many other generic universal USB adapters on sale for cheap, but it'd be a great advantage to have the USB function incorporated into this universal travel adapter. However, there are some negative reviews posted on Amazon.com about how it failed to charge their USB devices. Now I wonder.