if you install from Nokia Software updater or other custom way of installing rom YES (but usually contacts, sms, photos in camera roll, saved pictures are uploaded already ifyou switch on the 'backup' function in the settings) but it will remember what apps you have installed and will re-install automatically after the update (you will lose all specific data related to the app eg: angry birds progress..etc)
Other storage is still there, it has been fixed in the sense that it is controlled not to leak or overshoot thats all.
Wait for the OFFICIAL OTA UPDATE (sorry for the cap) which will come to you in due time on your phone and just update with that which will not disturb your files hopefully (had not had this so cannot really be 100% sure)