So I ran the upgrade on an existing 1.9.1 database and had the following problems:

1- The provider scripts did not automatically run, I had to run them manually.

2- The user migration steps do no execute.

3- The passwords got messed up. I had to use the lost password function to reset the admin password and then reset each user's passwords manually.

I got the same problem with passwords. Did not check the other things though. I see that the upgrade did not change the password hashes in the database so it must be a comparison that is done different.

I used the latest version from SVN from yesterday.