The main hook here would seem to be for Dropbox users; if you've got music stored in OneDrive, you're probably listening to it with Xbox Music. And I'm not sure why you'd be uploading stuff to Google Drive yet not taking advantage of Google's free, music-focused storage that lets you store 50,000 songs for free. DoubleTwist has actually taken a pretty hash stance against Google, targeting the company's music policies in a blog post:

We created CloudPlayer to provide an alternative to crippled, proprietary cloud music lockers that impose painful restrictions on what you can do with the music you own. These user-hostile terms are usually hidden in the fine print of cloud music offerings by major corporations and impose arbitrary limits on the number of "authorized devices", restrict the number of times you can download your music, and penalize music enthusiasts who own multiple gadgets or frequently upgrade their phones and firmware.

CloudPlayer has a nice look that sticks closely to Google's Material Design with some extra flourishes here and there. Album and artist titles pull their color from cover art, and the Now Playing screen has a slick pull-up menu for seeing what's next in the queue. The app supports high-fidelity formats like FLAC and offers offline playback for whenever you'll be without Wi-Fi or cellular data. Other than barebones features like playlists, star ratings, and a 10-band EQ, there's not much else in the way of standout features. (Chromecast and AirPlay support are nice inclusions, though.) In my brief hands-on time, playback was fine without any annoying stuttering or buffering, but this will obviously vary based on the quality of your connection.

To me, CloudPlayer seems like it's made for two types of people. The first is someone who's meticulous about his or her music library when it comes to file quality, metadata tagging, and album artwork. The second would be people who simply don't have Spotify or other services available in their region. If you're not either type, you'd be far better off using one of the big streaming services. They're simpler to use and offer a lot more.

And DoubleTwist's latest app isn't the only one of its kind; other music players for Android can also tap into cloud storage, or even retrieve media stored on your computer or networked drive at home (i.e. Plex). CloudPlayer definitely works if you want a simple way of playing the music you've got sitting in Dropbox or quickly listening to uploads for cloud accounts you share with friends. But keep in mind after an initial weeklong trial, you'll have to pay $4.99 to unlock permanent cloud-based playback. That's on top of whatever your Dropbox, OneDrive, or Google Drive storage plan costs.