This is my review of both USB drive programs for running portable applications. This review is my own opinion so if you don't agree, well, that's your problem and I can't help you out.
U3 installation is very simple and when you first plug in your jump drive it will automatically start an installation wizard. This can be a pain especially if you are using an older computer (like the one I'm on) that only has USB 1.1. They recommend USB 2.0 but you can get away using 1.1 if you are patient and ready to wait a while for applications to load. PortableApps installation is very simple that probably a new user could figure out. You just download it and then extract it to your jumpdrive, then install it. This process took me a while longer than it should have since I am using an older computer. The install time was not long at all considering the USB speed.
Ease of Use U3 is very simple to use but their website is down so you are only able to get a handful of applications. The ones that you can get are pretty good. The load time is okay but you are almost better off just waiting until you get home to do some of the stuff. With PortableApps you can run quite a few programs. The load times of these programs are impressive. I was very impressed how well the U3 and PortableApps programs worked after loading. You would have thought that the programs were installed right on the computer.
The verdict Overall both applications have their ups and downs. U3 is very slow loading and has a smaller database of applications to use. PortableApps is a much quicker program and loads the applications much faster and are very easy to install.