Upgraded from 5.1 to 5.2. There are some issues with modules, and some will have to be looked at again to work properly with 5.2, such as IMCE and IMCE Gallery. Although I can tolerate some modules' new oddities, not having new users to be able to register, get an initial e-mail, and login now is not acceptable.
System: Apache 1.3.33 with MySQL 4.0.21 and Php 5.2.2.
New users who register with the site are not getting confirmation e-mails from the system with their user name and initial password, a process which worked flawlessly in 5.1. When I investigated, I found an entry is made in the MySQL database showing a user name and encrypted password, and an e-mail sent to the Site Administrator announcing that someone has registered is sent out. BUT new users never get their initial e-mail with their user name and initial password to get them started.
Looking at my Site Administrator e-mails and Drupal logs, I can see new people trying to register. And, although I haven't lost any of my current users, no new users seem to be able to join the site. I've seen some people who applied for accounts trying, and failling, to log in, even though they never got an initial e-mail. Apparently, they have more confidence in the registration system than I do.