Im using Ajax register 1.5 in my site but there is small bug.
When new user register to site everything look ok and user can login and make everything he allowed.
When a user registers to the site as AJAX to put it to another "registered" usergroup does not really registered in the Joomla usergroup.
I noticed this when I use the Online User module which displays the user usergroup. New registered users it does not recognize registered on.
With Joomla's own sign-up system, everything works ok. So the Bug is in Ajax register.