So you need to get some files from your phone into the cloud? FolderSync is one of the most popular ways to do it. This app gives you very fine control over what files go where and when, and today it's getting a sizable update to v2.7 with a bit of a UI makeover and some new features.
Here's the full changelog.
Provider: added support for Amazon Cloud Drive.
GUI: support for Android 5.0 Material style and multiple themes.
GUI: use right drawer menu to access cloud and favorites in file manager (buttons in actionbar removed).
Feature: support for uploading large files to OneDrive.
Feature: support for external SD card on Android Lollipop (use external storage permission in settings).
Feature: root write support (experimental).
Feature: added wizard to help create sync
The UI before was very "holo," but it's in-line with the basics of material design now. There are even a few different theme options. The UI will look best if you're on Android 5.0, and you'll also have SD card write support again. There's also preliminary support for SD write with root, but no promises on that. There's a free trial version of FolderSync if you want to check out the new features.