Also consider Kohana. CodeIgniter has something of a problem in that the devs aren't really updating it much these days or considering community suggestions. They've gone a fair ways recently to try to fix this problem, but a lot of good devs have given up and moved on.

Kohana broke off from CodeIgniter long ago, and has since embraced PHP 5.3 (No more $this->something->something_else->some_function() spam all over the place). It's nowadays a pretty different creature from CI, and IMHO far superiour.