Frontend form field labels are not styled well on Joomla 3
As shown in this screenshot, the field labels have an ugly grey background and white text applied to the .label CSS class, at least on the Joomla 3 default 'Protostar' site (frontend) template.
Of course this could be overridden by a savvy user with custom CSS but it does degrade the out-of-box experience for a new Joomla 3 user.