I have updated the beta to fix the issues Jason pointed out. The .htaccess file no longer makes mod_rewrite look for user. Instead I have introduced a new permission called 'edit drupal users'. If your role has this permission then you will not be redirected to the phpBB profile.
If you modify usernames, email, password or pictures through Drupal you will end up with a mess in your database. Therefore only key admins should have this permission.
To update you should replace all the files and check the configuration file. You may also have to customize the .htaccess files, though they should be path agnostic.
I have not included the patch suggested by SpectralDart because I remain unconvinced that it makes a difference, but I am flexible about this if anyone can explain it.
One thing I forgot to mention earlier: The module uses Drupals database abstraction system and uses fairly simple queries. I therefore expect it to work on all databases that are supported by both Drupal and phpBB 3.x. Let me know if you are using it on Postgresql or anything other than MySQL :)