iCloud Drive is less flexible than other cloud storage services, such as Dropbox, Box.com, Google Drive, OneDrive, and MediaFire. Outside of the options available in the Sharing menu you can’t share and sync your iCloud Drive documents with others, for example, thus making document collaboration tricky. With these third-party storage services you can send a link to anyone so they can download a file. With iCloud Drive you can share files this way only with documents created with iWork apps. iCloud Drive has other limitations as well. You’ll need OS X Yosemite and iOS 8 and you can’t save files larger than 15GB, for example.
iCloud Drive isn’t as powerful as Dropbox and other competitors, but for many customers it will be sufficient. And even though I wouldn’t live without Dropbox at this point, for the sake of some of my workflows, iCloud Drive is better suited.
Read Macworld’s article if you want to get a complete introduction to iCloud Drive. ∞