The operating system offers you a virtual hard disk of 15GB. You can avail a bonus of 5GB by inviting friends i.e every time a persons joins ghost through your reference, 5GB of space is added to your virtual disk.
Ghost also provides other utility tools such as office softwares called Zoho write, Zoho sheets(very similar to open office) and items included in vista sidebar such as sticky notes etc. The interface is very user friendly. And as it has been developed on a flash platform it uploads really fast. 
The best feature is 'bulk upload' which is very similar to FTPs, almost same as filezilla. You can drag and drop files from you computer's hard disk onto your virtual computer.
There is a lot to explore in Ghost. Try it today and if you need an invite just leave your e-mail in the comment box.
