This is just an alternative to OneDrive – it’s actually a smart move since there are many folks who use Dropbox. Users can thus move their files more seamlessly as a result.
Again, if there is one area that Apple continually disappoints in, it’s in their web services area. iCloud Drive is the worse since it mandates Yosemite (whereas iCloud Drive for Windows supports the previous Windows 7 in addition to 8). What’s even more ironic is OneDrive has support all the way back to Mac OS X 10.7.3 (Lion).

In otherwords, Microsoft’s OneDrive offers far more compatibility with not just older Mac operating systems, but also works with iOS 7 devices. It doesn’t require the maddening sort of hoop jumping that Apple enforces with their annual operating system upgrades, and tying certain features and services to that latest operating system.
Because I refuse to upgrade to Yosemite, I actually began making much more use of OneDrive (I’ve already been using Dropbox but have only 2GB of space, whereas Microsoft provides 30GB free. iCloud provides 5GB free). I could pay for more space but right now, I’m evaluating based on the non-paying options. Microsoft’s generous offering actually makes their cloud services stickier for me. Yes, this is bizarro world; the cloud is meant to be the glue that binds users to a particular ecosystem. Myself, I’m barely making use of Apple’s cloud services.
If Apple officially supported more user interface customization (such that Yosemite’s eyesore UI can be dealt with), I wouldn’t be this adamant about seeing Microsoft succeed with Windows 10.