Thoughts on Codeigniter?

Hi all,
I'm building a classifieds ads website, similar to that of craigslist.
I have already coded a complete login/registration system primarily with php for the backend stuff connecting to a MySQL database, but I wanted to move onto creating a "post ads" function next.
I was wondering if I should start to use Codeigniter because I have heard its a pretty good framework for building web apps.
What are your thoughts on CI reddit? And any tips for someone building a classifieds ads website? What other languages should I be focusing on besides php/html/css?usps tracking showbox speed test