Its arrival is planned for this fall but icloud is already available in beta today. The basic package of 5 GB will be 100% free, but in addition to this, there will be three other possibilities of extension at 10, 20 and 50 GB for 20, 40 and $ 100 per year. For comparison, Dropbox offers 2GB for free, 50 GB for $ 120 and 100 GB for $ 240. However SkyDrive Microsoft offers for its part 25 GB free.
Remember that the Apple service icloud synchronize between their servers and devices and IOS Mac, iPhone photos, iWork documents, applications, books and backup IOS, but also contacts, calendars and emails. Be careful though! Those who already subscribe to MobileMe will lose their synchronization Keychain Access containing all their passwords, their photo gallery, publications iWeb and iDisk from June 30, 2012.