I upgraded last night (thankfully I made a backup of the db and iis folder :) ) and here are the issues I am having:
a. The admin account for the main (and only) site is fragged. When I login as admin all the content in all the blocks go away as if i do not have access to any of it. However if I login as host everything seems (from my limited testing so far) to work ok.
b. registering as a new user, then unregistering put your in this 1/2 logged in half not mode. Where you still got the logout link on the top of the page and access to some modules as if you are still logged in but no name and missing creditials in other parts. The full unregister/compleate logout does not take effect until you manually click the logout link.
c. Regular users have logged in and posted in the forums since the upgrade so as far as I can tell regular users have not been effected (so far).
d. I tried deleting some pages as admin and it would tell me they were deleted but still appeared. However it would allow me to create them. I feel this issue is related to the bug listed in a. I have not tried to do such as host account yet so do not know the results.
To do a restore back to the 4.5.5 backup I made last night before the upgrade all I need to do is over write my archive of the iis folder and in mssql do a restore from the backup I made, correct?
e. I have rebooted the server after the upgrade with same issues.