Lincoln Stein himself uses the functional interface in all his training examples. I can see three times to use the object interface (mind you I just woke up five minutes ago {grin}):

• When I'm unsure if saying use CGI qw(:standard) will collide with existing subroutines, such as grafting a CGI front onto some previous command-line program
• In a mod_perl environment, to keep from creating 240 stabs (as we discussed earlier in a thread about CGI.pm's performance) in each Apache::Registry-managed handler
• When I want to have more than one CGI object in a single program (to save and restore parameters to persistant storage, for example)

Other than that, use the functional form! Much less typing.

-- Randal L. Schwartz, Perl hacker