Is iCloud photostream private?

I have had my iphone for a couple of months and have my photos set to backup to icloud, but someone has just told me that they think anybody who has my apple ID can see these photos? Is this true?!

No, it's privately backed up onto iCloud so you may only retrieve it with your valid identification (i.e. Your password corresponding to Apple ID. The data may not be accessed unless on a device linked to your iCloud account or unless you login to iCloud.com to retrieve files.

To share files, you may wish to share via twitter or facebook or other, but iCloud currently has no sharing facility, although sharing is easy to accomplish over certain social networks and email.

You have 5GB free storage to back up data from any of your Apple devices or iCloud.com and any uploads to it are private