So I've been hacking away happily with Catalyst on my VegGuide.Org 3.0 project for quite some time, and I'm still liking Catalyst, which is a good thing
When I first started this project, I also looked at Jifty. It looked neat, but
Jifty, like Rails, is opinionated software. It has opinions about what ORM you should use, as well as what templating system you should use. It's ORM has opinions about your schema design, much like Rails (ugh, id is the worst column name evah!).
There's nothing wrong with opinionated software. I'm certainly opinionated myself. The problem with opinionated software is that it's really only appropriate for writing an app from scratch.
The main focus of my VegGuide 3.0 project is to completely revamp the UI of the site, and improve the user experience. I'm also aiming to make the system as RESTful as possible. Along the way, I'm slipping in some features like Google Maps integration, but mostly it's about UI & REST.
The existing VegGuide code uses Alzabo as its ORM. I like Alzabo, since it mostly does exactly what I want, though I'm not sure I'd recommend it to others for new projects these days. Nonetheless, I don't want to switch to another ORM as part of this project.
All this gets back to the opinionated software thing. I could've tried to integrate my Alzabo-using classes with Jifty, but it would've been a huge (perhaps monumental) amount of work. Catalyst, OTOH, has very few expectations. In fact, the core Catalyst code has no expectations of a model, you don't even have to have one!
This has made revamping the controller and view (UI) pieces of my app much easier, because I can reuse my existing model code without any changes to accomodate my framework. In a few cases, I've had to make some custom bridge code to make plugins (Session, Authz, etc) work with my model, but this has really been trivial to implement.
With Catalyst, you can convert an existing app to Catalyst without rewriting every aspect of the app in one fell swoop. That is a huge plus for Catalyst in my mind, since 100% rewrites are rarely possible. This may in fact be the number one selling point of Catalyst. Better code for old apps!