I first stumbled on this module from a CPAN search for json and it fit my needs at the moment and it may fit yours, but with more experience, I've moved to JSON::Syck. My usage doesn't need anything other than parsing or exporting JSON data, so a lot of what JSON offers is irrelevant. More importantly and objectively, JSON::Syck is faster (over 370% on my box!!).
I haven't worked with many web frameworks and actually, CGI::App is my first, but I just haven't had the need to move to anything else. This framework gives me a LOT of control and there are scores of Plugins that provide further functionality when & if I need them. Great mailing list, great people and great IRC channel (#cgiapp on irc.perl.org). I've coded a ton of web apps with cgiapp for QSR Magazine & Fine Books Magazine as well as some internal stuff. You can also do the fancy AJAX stuff with cgiapp, too ... it really is awesome stuff and I love it to pieces! :)
This is an AWESOME module, merging in Data::FormValidator's power with cgiapp's runmodes, templates and HTML::FillInForm to give the programmer an extremely easy way to enforce valid user input and at the same time, give the user a user-friendly method for correcting their errors.