Apple has released iCloud Drive for Windows, but you can't yet use the feature on a Mac.
One of the key features of iOS 8, and the whole Mac ecosystem as a whole, is iCloud Drive. This is basically Apple's take on Dropbox, a slightly more flexible take on cloud storage than the original iCloud system.
That's great and you can activate iCloud Drive on your iOS 8 device right now. But there's a catch, you can't use it on a Mac unless you're running the Yosemite beta.
Yet you can access iCloud Drive on Windows thanks to the newly released app. iCloud for Windows isn't as advanced as it is (will be) on Macs, but you can still access all your documents from various applications such as Keynote, Numbers, Pages and more.
The features you don't get on Windows include the iCloud Keychain password system and access to Notes, but it's still a useful way to access your iCloud documents from your Windows PC. And if you get the chance you can show any Mac owners you know what it looks like.
If you're Mac owner, your best bet is to try the Yosemite public beta. We've been using it for weeks without any problems, so there's little to fear from trying it out.
Next, read our Google Drive vs iCloud Drive vs Dropbox vs One Drive comparison