CiviCRM is a large and complex application. Much of its functionality is covered by unit tests to prevent regressions, and there is a rigorous review and testing process for changes made to the stable releases. However neither of these are foolproof and sometimes things break. We rely on the goodwill of community members such as yourself to find bugs and contribute toward fixing them in a timely manner. Once identified, critical bugs are often solved in a matter of days.
I just tested on a couple of systems and this bug is unusual in that it seems to affect Wordpress (and reportedly Joomla) but not Drupal. That's odd since the CiviCRM core application is identical for all 3 CMSs, and that oddity no doubt contributed to this one slipping through the cracks.
An issue has been filed in the bug tracker for this and it's been marked as critical so it will get highest priority from the core team. If community members step in with debugging info or patches that will move things along even faster.