I think I remember Guido making the comment that Twisted and/or Nevow scared him. I also think that (ignoring the causal effects of his statement) many people feel the same way, and if those people saw this blog post, they'd say I was deluded.
I've been using Nevow (on and off) since fzZzy first presented it at PyCon2004. I've been blogging about it since a year after that.
My first "web framework" was shell-script-generated HTML in the mid-90s. Then I found PHP. Zope. Perl (Interchange and Mason). Plone. Then a whole string of custom solutions.
I tried Django when it first came out, and hated it. I tried it again recently, and was most pleased with the progress they've made. I'm using it on a project with some non-programmer folk who wanted to convert their application from PHP to Python (I couldn't sell them on twisted). After digging around in the Django code base, I can safely say I will probably enjoy myself while working on the project.
I've also been a fan of the z3 CA for a couple years, and disagree with much of Ian Bicking's recent assessment of it (and agree very strongly with Martijn's comments). I continue to do work with z3 and enjoy almost all of it (being able to pick and choose helps greatly).
But when it comes down to it, when I need to roll something out fast, and I can choose the framework without concern for such things as technical support, community popularity, buzz, or political considerations, I choose Nevow. Case in point, the project I mentioned in this post. 30 minutes to casually convert a project from z3 to Nevow.
Though important, development speed is not the only consideration to make. Everyone talks about how fast you can roll a project out in web framework X, etc. But there's something that has a much higher priority for me: how insane will it let me be? Can I do anything I want? Once it's built, can I plug "stuff" in and out? Can I make unexpected changes easily and quickly, without compromising the integrity of the architecture? And even more: can I build my own system(s) with it?
And that's where Nevow cinches it for me. I am the most comfortable with it's design, templating, internals, and programmer freedom. I feel I have a little more freedom and flexibility with it than I do with z3. Nevow provides me with the tools and comfort level to build my own systems easily, quickly, and extensibly.
As an example, take this work in progress.
I've built a couple game-world oriented sites in the past. The first one used PHP and the second two used Plone. In both cases, it was very difficult to easily manage what I wanted to manage. I learned a lot of lessons about how information management works for me. When I started working on Myðgarður, I put these lessons into effect. Nevow let me do that.
I have a highly customized brain that needs things done in a certain way in order to be maximally productive. I think lots of brains are like that ;-) I want a framework that reflects my brain's needs, not only to deliver a result quickly, but to deliver it in a way the fits me best... and can adapt to the future best.
As a side note, Nevow is going through an overhaul (more) right now that will not only improve its general efficiency, but will actually fit my brain even better. When the context-less Nevow is released, I plan on producing at least one screencast on how to go form 0 to 60 with it in less than 20 minutes.
So stay tuned...