ES File Explorer has been on my phone for a long time. I love using it to manipulate and move files to and from various folders and the like. My only complaint was that the UI seemed a bit outdated and didn’t fit with the Holo style that the later versions of Android brought to the table. The devs must have read my mind though because they posted a test build of the newest version of the file manager sporting a new Holo-style theme. While it is marked for testing purposes, the app appears to be pretty solid. I have yet to see a hiccup in the short time that I’ve used it.
For those that are interested in tinkering with the app, you can download it or read up on it from the source link below. I’ve included a gallery past the break so that you can see the new UI in action. It should hit the Play Store sometime soon barring any major bugs. As far as I can tell though, it’s pretty close to a final product.