I'd be interested in hearing how well-suited CodeIgniter is for a web-application that will be brought FAR beyond just presenting blog-like content. What I intend to build will be a full-blown web-based app.
I'm about to start a new project, and thought I'd settled on CI as my framework of choice (never coded w/ a framework, so trying to get it 'right' on my first try), but some of the comments I've read here and elsewhere have me second-guessing my choice.
I'd heavily advise ditching CI and hacking around with Kohana Version 3. Despite my misgivings it is super fast, super extensible and extremely powerful.
CI is just not updated enough IMO to form the stable base for an app.
As for taking it beyond blog content - I've created all sorts of complex sites; for example featured realtor website (property search, user management etc.) a wiki/"stackoverflow similar" site and am also working on a twitter "ticket" and marketing site (which is pretty complex). So it is suited to stuff like that.
For blog variants I have mostly used Drupal and I have a couple of blogs using Wordpress. Don't underestimate the power of both of them and that is one reason why I am still sticking with PHP for the forseeable future. I can attach a Wordpress installation to a CodeIgniter framework and with very little additional work, I can have a blog working - albeit with ugly code! After all wordpress is only 10 tables, Drupal is about 50.