Well if you read my posts you'll see that's not what happened - on two different phones. Both phones have significantly less free space after the update, but my 5s has a lot less.
I have no clue what happened on your device. But I don't see everyone else complaining about losing 1 or 2 gb of storage. It simply doesn't do that. Your issue is something else. Try a restore as new. Not from a back up.
I just finished installing IOS 9, I was going to do it through iTunes but forgot. Anyway it went like a dream (Only took just under 40 minutes in total) I started with 9.5GB of free space and I still have the same.
I was forced to do a system restore for ios 9.0.2 and before i had been maxing out on my 16gb phone after the restore i got back 1.5 gb Sent from my iPhone using Tapatalk