I've built an AJAX-powered CMS with Catalyst, about 6_000 to 8_000 loc without templates and have to say it was fun.

I especially like the easy PlugIn mechanism. If I needed functionality that acts deeper in the guts of Catalyst and not in application-level, I just wrote a (reusable) plugin. Other +'s I found:

- Really fast development
- Applications are easy to refactor
- codeparts easy to reuse.
- Many Plugins and an easy plugin-mech so it's mostly not a big deal to write a plugin around a needed module.
- Understandable sourcecode
- fast and active developer-community